Add a shortcut key to toggle braille viewer. (#13265)
Link to issue number:
Fixes #13258
Summary of the issue:
In #13258, it was asked to have a gesture to toggle braille viewer activation/deactivation as it already exists for speech viewer. It is not very clear why there was a gesture to toggle speech viewer and not for braille viewer.
Description of how this pull request fixes the issue:
Created a script with unassigned gesture in the global commands to toggle the braille viewer.
Updated the user doc
