Follow up of #14503: Move extension points to top level module and fix FilterValueT name

[LeonarddeR]

Link to issue number:

#14531 (comment)

Summary of the issue:

1. FilterValueTypeT nneeded renaming to FilterValueT and had a wrong string in its TypeVar declaration.
2. When experimenting with the extensionPoints, particularlyy with registering a handler to decide_executeGesture in a braille display driver, I discovered that inputCore was not yet initialized when initializing the driver and therefore extension point registration failed.

Description of user facing changes

Moved extension points, changes file is changed as part of this pr to reflect this.

Description of development approach

Just moving and renaming code

Testing strategy:

Unit tests should cover this, I manually tested the braille viewer.

Known issues with pull request:

None known

Change log entries:

In PR diff

Code Review Checklist:

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

[AppVeyorBot]

• PASS: Translation comments check.
• PASS: Unit tests.
• PASS: Lint check.
• FAIL: System tests (tags: installer NVDA). See test results for more information.
• Build (for testing PR): https://ci.appveyor.com/api/buildjobs/tlj4gvo6dwjwta49/artifacts/output/nvda_snapshot_pr14549-27539,7334a18b.exe
• CI timing (mins):
  INIT 0.0,
  INSTALL_START 0.8,
  INSTALL_END 0.9,
  BUILD_START 0.0,
  BUILD_END 23.3,
  TESTSETUP_START 0.0,
  TESTSETUP_END 0.3,
  TEST_START 0.0,
  TEST_END 18.8,
  FINISH_END 0.1

See test results for failed build of commit 7334a18bd2

[AppVeyorBot]

• PASS: Translation comments check.
• PASS: Unit tests.
• PASS: Lint check.
• Build execution time has reached the maximum allowed time for your plan (60 minutes).

See test results for failed build of commit da3e382f47