Message Dialog API take 2

[SaschaCowley]

Link to issue number:

Closes #13007
Closes #12344
Closes #12353

Summary of the issue:

This is the second PR to merge the message dialog API into NVDA. The previous merge was at f437723.
See #17304 for full implementation details.
The original PR was reverted by #17561, due to #17553 and #17560.

Description of user facing changes

This PR does not, in itself, introduce any end-user facing changes. However, it lays the groundwork for closing a number of issues.

Tasks

• Fix the COM registration fixing tool (It seems that the registration tool is not working. #17560)
• Fix NVDA updates (cannot update to current alpha #17553)

Description of development approach

Restored gui.nvdaControls.MessageDialog inheriting from ContextHelpMixin, which was accidentally lost.

Changed updateCheck.UpdateAskInstallDialog.onUpdateButton and onPostponeButton to simply end the modal, returning the appropriate code. Added a static method to UpdateAskInstallDialog which returns a callback function which, when given the return code from UpdateAskInstallDialog, performs the appropriate action. Added a property method to generate this callback function given the attributes of the instance on which it is called.

Testing strategy:

Created a portable copy of NVDA (scons dist), and tested running the CRFT:

• Running and granting permission - works as expected
• Running and denying permission - works as expected
• Cancelling - works as expected

Added updateVersionType="snapshot:alpha" to source/versionInfo.py`, and tested updating with NVDA running from source:

1. Attempt updating via NVDA menu -> Help -> Check for update... -> Download update -> Update - works as expected
2. Update by downloading then postponing update, then exit NVDA -> Install pending update
   1. Without incompatible updates installed - works as expected
   2. With incompatible updates installed - works as expected
3. Update by downloading then postponing update, restarting NVDA, then NVDA menu -> Install pending update - works as expected
4. Update by downloading then postponing update, restarting NVDA, then accepting the prompt to install the update - works as expected

Known issues with pull request:

Code Review Checklist:

• Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• API is compatible with existing add-ons.
• Security precautions taken.

@coderabbitai summary

[seanbudd]

New changes look good