Enable editor when double-clicking on stamp annotation

[nicolo-ribaudo]

In Firefox, double-clicking on a stamp annotation triggers text selection (selecting the last text element in the dom before the annotation): this triggers the logic to make annotations not interfere with text selection, which in turns prevents the double click from triggering the annotation editor.

This commit fixes the problem by making annotations non-selectable, so that clicking on them does not trigger text selection. Freetext annotations were already non-selectable, so this commit doesn't change that. However, we need to explicitly mark text in popups as selectable.

Fixes #19315

Note that only annotations that are included in the PDF are editable by double-clicking on them. All user-created annotations are not, because they are only in the annotationEditorLayer what has pointer-events: none.

[Snuffleupagus]

Unfortunately the new test doesn't seem to work on the bots, since both logs contain:

3) Stamp Editor Switch to edit mode by double clicking on an existing stamp annotation must switch to edit mode
  Message:
�[31m    Expected 'annotationEditorLayer disabled' to contain 'stampEditing'.�[0m
  Stack:
        at <Jasmine>
        at file:///home/ubuntu/pdfjs/botio-files-pdfjs/private/20f512b4c185955/test/integration/stamp_editor_spec.mjs:1843:43
        at async Promise.all (index 1)
        at async UserContext.<anonymous> (file:///home/ubuntu/pdfjs/botio-files-pdfjs/private/20f512b4c185955/test/integration/stamp_editor_spec.mjs:1833:7)

[nicolo-ribaudo]

Taking at the look at the failure, since it seems likely to be caused by my changes

[moz-tools-bot]

From: Bot.io (Windows)

---

Received

Command cmd_integrationtest from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.193.163.58:8877/1ec021137f9e021/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

---

Received

Command cmd_integrationtest from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.241.84.105:8877/753b7df4a6ab1dd/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

---

Success

Full output at http://54.241.84.105:8877/753b7df4a6ab1dd/output.txt

Total script time: 10.50 mins

• Integration Tests: Passed

[moz-tools-bot]

From: Bot.io (Windows)

---

Failed

Full output at http://54.193.163.58:8877/1ec021137f9e021/output.txt

Total script time: 25.87 mins

• Integration Tests: FAILED

[Snuffleupagus]

r=me, thank you.