Provide more help around GRANT errors, particularly for missing TEMPORARY TABLE permission

Summary:
Fixes T13622. Figuring out what permissions we have seems difficult, so address this a bit more narrowly:

  - Make the "access denied" error message a bit more helpful.
  - Tailor error handling for the "CREATE TEMPORARY TABLE" statement.

Test Plan:
  - Created a new user, granted them "SELECT ON *.*" but not "CREATE TEMPORARY TABLE", ran `bin/storage upgrade --force --apply phabricator:20210215.changeset.02.phid-populate.php`.
  - Before: fairly opaque error.
  - After: fairly useful error.

Subscribers: PHID-OPKG-gm6ozazyms6q6i22gyam

Maniphest Tasks: T13622

Differential Revision: https://secure.phabricator.com/D21608

resources/sql/autopatches/20210215.changeset.02.phid-populate.php

@@ -11,12 +11,20 @@ $chunk_size = 4096;
 
 $temporary_table = 'tmp_20210215_changeset_id_map';
 
-queryfx(
-  $conn,
-  'CREATE TEMPORARY TABLE %T (
-    changeset_id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
-    changeset_phid VARBINARY(64) NOT NULL)',
-  $temporary_table);
+try {
+  queryfx(
+    $conn,
+    'CREATE TEMPORARY TABLE %T (
+      changeset_id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+      changeset_phid VARBINARY(64) NOT NULL)',
+    $temporary_table);
+} catch (AphrontAccessDeniedQueryException $ex) {
+  throw new PhutilProxyException(
+    pht(
+      'Failed to "CREATE TEMPORARY TABLE". You may need to "GRANT" the '.
+      'current MySQL user this permission.'),
+    $ex);
+}
 
 $table_iterator = id(new LiskRawMigrationIterator($conn, $table_name))
   ->setPageSize($chunk_size);

src/infrastructure/storage/connection/mysql/AphrontBaseMySQLDatabaseConnection.php

@@ -347,7 +347,16 @@ abstract class AphrontBaseMySQLDatabaseConnection
       case 1142: // Access denied to table
       case 1143: // Access denied to column
       case 1227: // Access denied (e.g., no SUPER for SHOW SLAVE STATUS).
-        throw new AphrontAccessDeniedQueryException($message);
+
+        // See T13622. Try to help users figure out that this is a GRANT
+        // problem.
+
+        $more = pht(
+          'This error usually indicates that you need to "GRANT" the '.
+          'MySQL user additional permissions. See "GRANT" in the MySQL '.
+          'manual for help.');
+
+        throw new AphrontAccessDeniedQueryException("{$message}\n\n{$more}");
       case 1045: // Access denied (auth)
         throw new AphrontInvalidCredentialsQueryException($message);
       case 1146: // No such table