First of all many thanks to @JulienCochuyt for most of this work.

Link to issue number:

Fixes #6769
Superseedes #12371

Summary of the issue:

Currently, the Window File Explorer cannot be retrieved using the reportStatusLine global command.

Description of how this pull request fixes the issue:

• Take advantage of Status bar handling: allow app modules to define their own routines to fetch status bar and use it in status bar command in global commands #4640 to implement custom status bar retrieval by the explorer app module.
• Use a UIAWalker to retrieve it, as hinted by @josephsl in Can't read status bar in File Explorer (Windows 10) #6769 (comment)
• Still, instead of overlaying the status bar of its children for concerns expressed in Can't read status bar in File Explorer (Windows 10) #6769 (comment), allow app modules to provide their custom implementation of api.getStatusBarText
• Implement explorer.AppModule.getStatusBarText as inspired by @ruifontes prototype in Nvda utters unavailable after copying files #6842 (comment) (hinted by @feerrenrut in Can't read status bar in File Explorer (Windows 10) #6769 (comment)) but in a slightly more complex way - trying to cover more unexpected cases.

Testing strategy:

@JulienCochuyt 's testing:

• Ran from source under Windows 10 20H2 19042.928 & 19042.964 both with a French locale.
• Ensured expected result whether files are actually selected or not.

Additionally I've tested under Windows 7, Server 2012, Windows 10 1511, 1809 and latest preview of Windows 11 - in all cases status bar has been retrieved successfully.

Known issues with pull request:

May possibly not work under some version of Windows not described in the testing above, but since this code works from Server 2012 up to Windows 11 without any changes I consider this pretty unlikely.

Change log entries:

Changes

• In Windows 8 and later , the File Explorer status bar can now be retrieved using the standard gesture NVDA+end (desktop) / NVDA+shift+end (laptop).

For Developers

• Status bar text retrieval may now be customized by an AppModule.

Code Review Checklist:

• Pull Request description is up to date.
• Unit tests.
• System (end to end) tests.
• Manual testing.
• API is compatible with existing addons.
• User Documentation.
• Change log entry.
• Context sensitive help for GUI changes.
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers

Changes from #12371 :

• Tested and modified to work under Windows 7 as requested by @michaelDCurran in Support retrieving the status bar of Windows File Explorer (#6769) #12371 review.
• Eliminated garbage reported when retrieving status bar in Windows 10's quick access
• Converted to use new enums from controlTypes
• Removed redundant announcements about no files being selected.