Braille: switch showing selection with dots 7 and 8 on/off

[burmancomp]

Is your feature request related to a problem? Please describe.

Selected text is shown with dots 7 and 8 in braille. Problem is that reading of selected text is quite slow and difficult.

Describe the solution you'd like

Possibility to switch selection on/off from settings and with input gesture.

Describe alternatives you've considered

Adding new braille setting with feature flag and input gesture.

Additional context

[irrah68]

I have noticed that when I press NVDA+Down and try to read from my Braille display at the same time when the speech synthesizer is talking, it is quite a difficult to read Braille because of these extra dots 7 and 8 being up all the time. It is a good idea to add a new feature, where an user can decide and choose if she/he wants to read Braille without dots 7 and 8 when reading continuously.

[burmancomp]

I can try to implement this.