Workboard: Milestone Name easily editable (instead of surfing 3 pages)

Summary:
After this change, a new input field "Milestone Name" appears in the "Edit" menu of a Milestone:

| Before    | After     |
|-----------|-----------|
| {F314008} | {F314005} |

So you can quickly change the name of your Milestones, from a Workboard.

Before this change, from a Workboard, this was the way to rename a Milestone:

1. click on the Milestone name (yes, that is a link)
2. click on Manage
3. click on Edit Details
4. rename
5. Save
6. Manually visit again the Project's Workboard

After this change, from a Workboard, you just need to:

1. click on Milestone > Edit
2. click on Edit Column
3. rename
4. Save

Example usage:

{F314015}

This does not change the level of permissions needed: if you have not enough
permissions to see or edit a Milestone, you cannot access this feature indeed.

In short, this is just a frontend change, keeping current policies as-is.

Closes T15143

Test Plan:
Create a Project or use an existing editable one.

Create a Milestone called "Test Milestone". You can create Milestones visiting the Project's menu {nav icon=sitemap,name=Subprojects > icon=plus,name=Create next milestone}

Visit the Project's Workboard. Find the column "Test Milestone". Click the Edit button on a Milestone, and:

- try to save another name: it must work
- try to save an empty name: nice error message shown
- try to save both the score points and the name: it must work
- try to save "FOO" as Points: you still see the error message

Also:

- do the same for the Backlog column: it still works (name still allowed to be empty)
- do the same for a "normal" Column (not the Backlog): it still work (name still __not__ allowed to be empty)

Reviewers: O1 Blessed Committers, Cigaryno, 20after4, waldyrious

Reviewed By: O1 Blessed Committers, Cigaryno, 20after4, waldyrious

Subscribers: waldyrious, brennen, aklapper, 20after4, speck, tobiaswiese, Matthew, Cigaryno

Maniphest Tasks: T15143

Differential Revision: https://we.phorge.it/D25066

src/applications/project/controller/PhabricatorProjectColumnEditController.php

@@ -45,16 +45,32 @@ final class PhabricatorProjectColumnEditController
 
     $e_name = null;
     $e_limit = null;
+    $e_milestone_name = null;
 
     $v_limit = $column->getPointLimit();
     $v_name = $column->getName();
 
+    $proxy = $column->getProxy();
+
+    // Is this a normal Column? Example: when true, this is not a Milestone.
+    $is_column = !$proxy;
+
+    // Is this a Milestone? Example: when true, this is not a normal Column.
+    $is_milestone = $proxy && $proxy->isMilestone();
+
+    // Milestone name, eventually coming from the proxed object.
+    $v_milestone_name = null;
+    if ($is_milestone) {
+      $v_milestone_name = $proxy->getName();
+    }
+
     $validation_exception = null;
     $view_uri = $project->getWorkboardURI();
 
     if ($request->isFormPost()) {
       $v_name = $request->getStr('name');
       $v_limit = $request->getStr('limit');
+      $v_milestone_name = $request->getStr('milestone.name');
 
       if ($is_new) {
         $column->setProjectPHID($project->getPHID());
@@ -74,14 +90,22 @@ final class PhabricatorProjectColumnEditController
       }
 
       $xactions = array();
+      $xactions_milestone = array();
 
       $type_name = PhabricatorProjectColumnNameTransaction::TRANSACTIONTYPE;
       $type_limit = PhabricatorProjectColumnLimitTransaction::TRANSACTIONTYPE;
+      $type_project_name = PhabricatorProjectNameTransaction::TRANSACTIONTYPE;
 
-      if (!$column->getProxy()) {
+      if ($is_column) {
+        // Transaction for Column name.
         $xactions[] = id(new PhabricatorProjectColumnTransaction())
           ->setTransactionType($type_name)
           ->setNewValue($v_name);
+      } else if ($is_milestone) {
+        // Transaction for Milestone name (that internally is a Project Name).
+        $xactions_milestone[] = id(new PhabricatorProjectTransaction())
+          ->setTransactionType($type_project_name)
+          ->setNewValue($v_milestone_name);
       }
 
       $xactions[] = id(new PhabricatorProjectColumnTransaction())
@@ -94,24 +118,53 @@ final class PhabricatorProjectColumnEditController
           ->setContinueOnNoEffect(true)
           ->setContentSourceFromRequest($request)
           ->applyTransactions($column, $xactions);
-        return id(new AphrontRedirectResponse())->setURI($view_uri);
       } catch (PhabricatorApplicationTransactionValidationException $ex) {
+        // Error messages related to the Column (like invalid Name, etc.)
         $e_name = $ex->getShortMessage($type_name);
         $e_limit = $ex->getShortMessage($type_limit);
         $validation_exception = $ex;
       }
+
+      // Save Milestone-related stuff but only if there were no prior problems
+      // and only if we have changes.
+      if (!$validation_exception && $xactions_milestone) {
+        try {
+          $editor_milestone = id(new PhabricatorProjectTransactionEditor())
+            ->setActor($viewer)
+            ->setContinueOnNoEffect(true)
+            ->setContentSourceFromRequest($request)
+            ->applyTransactions($proxy, $xactions_milestone);
+        } catch (PhabricatorApplicationTransactionValidationException $ex) {
+          // Error messages related to the Milestone (like invalid Name, etc.)
+          $e_milestone_name = $ex->getShortMessage($type_project_name);
+          $validation_exception = $ex;
+        }
+      }
+
+      // Refresh the page only if there are no errors to show.
+      if (!$validation_exception) {
+        return id(new AphrontRedirectResponse())->setURI($view_uri);
+      }
     }
 
     $form = id(new AphrontFormView())
       ->setUser($request->getUser());
 
-    if (!$column->getProxy()) {
+    // Show the most appropriate input field for the name.
+    if ($is_column) {
       $form->appendChild(
         id(new AphrontFormTextControl())
           ->setValue($v_name)
           ->setLabel(pht('Name'))
           ->setName('name')
           ->setError($e_name));
+    } else if ($is_milestone) {
+      $form->appendChild(
+        id(new AphrontFormTextControl())
+          ->setValue($v_milestone_name)
+          ->setLabel(pht('Milestone Name'))
+          ->setName('milestone.name')
+          ->setError($e_milestone_name));
     }
 
     $form->appendChild(