Add pre_filter_speechSequence and post_filter_speechSequence extension point Actions

[beqabeqa473]

Link to issue number:

Superseeds #16213

Summary of the issue:

Add pre_filter_speechSequence and post_filter_speechSequence extensionPoint Actions, inject pre_filter_speechSequence just before filter in speech.speak and use post_filter_speechSequence in speechViewer as @LeonarddeR stated in #14520

Description of user facing changes

Nothing changed from user's point of view

Description of development approach

Removed code responsible for appending speechSequence to speech_viewer from speech.speak and registered appendSpeechSequence as extensionPoint handler function.

Testing strategy:

Manually tested that speech is still visible on the screen when activating speech_viewer

Known issues with pull request:

None at this moment

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