Context help: support more controls and dialogs (PR #11743)
* Context help:
- Added missing helpId in some dialogs/panels
- Fixed some helpId
- Added calls to self.bindHelpEvent
- Fixed parameters (anchor) of some calls to self.bindHelpEvent
* Changed the behaviour with voice settings:
- if the setting is a standard setting, go to the paragraph that describes this specific setting in User Guide
- if the setting is not standard, i.e. specific to a third-party synth, go to speech settings in the User Guide
* Rewrite rate boost paragraph as per review comments.
Fixes #7757
Follow-up of #11456
No change log entry required.
Co-authored-by: Reef Turner <reef@nvaccess.org>
