Drag & Drop: set a link as external

Summary:
Rest assured: external links remain evil, by default.

Don't adopt them randomly by induction.

Whether you believe it or not, this specific external
link merited some deep thoughts on Phorge:

- https://we.phorge.it/T15172

So, whenever you use a mouse, a finger, or whenever we have
a confirmation dialog or not to prevent onblur disasters,
this change is probably consistent with common expectations.

Having said, external links remain evil - by default.

Closes T15172

Test Plan:
- Drag & Drop a File on a Remarkup text
- click on the link inside the popup
- it opens in a new tab (without risk of form loss)

Reviewers: O1 Blessed Committers, avivey

Reviewed By: O1 Blessed Committers, avivey

Subscribers: speck, tobiaswiese, Matthew, Cigaryno

Maniphest Tasks: T15172

Differential Revision: https://we.phorge.it/D25077

webroot/rsrc/js/core/FileUpload.js

@@ -115,7 +115,19 @@ JX.install('PhabricatorFileUpload', {
 
       switch (this.getStatus()) {
         case 'done':
-          var link = JX.$N('a', {href: this.getPageURI()}, this.getMonogram());
+
+          // In this case the File upload was successful
+
+          var linkAttr = {};
+          linkAttr.href = this.getPageURI();
+
+          // External links are evil as default.
+          // Believe it or not, but some Phorge users brainstormed
+          // for one hour for this specific target="_blank".
+          // https://we.phorge.it/T15172
+          linkAttr.target = '_blank';
+
+          var link = JX.$N('a', linkAttr, this.getMonogram());
 
           content = [
             JX.$N('strong', {}, ['Upload Complete (', link, ')']),