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

When I encounter an issue in NVDA, I test with add-ons disabled if the issue still persists. If it does not, I have to find the add-on responsible for this issue by disabling some add-ons by dichotomy. Selecting or unselecting half of the add-ons one by one is tedious in a list of 15 add-ons or so.
Also being able to easily disable all add-ons but one would be very useful to test a specific add-on without any side effect of other add-ons.

Describe the solution you'd like

• Be able to select multiple add-ons in the add-on list
• For any multiple selection, be able to enable all of them or disable all of them; the "Enable add-on" and "Disable add-on" buttons should then be two separate buttons in order to address the case where some add-ons in the multiple selection are enabled and some other disabled.
• Also the "Remove add-on" button could be active for multiple selection to allow deleting many add-ons in one time.
• The "About" and "Help" buttons should be greyed out (disabled) in case the selection contains 2 or more add-ons.
• The "About", "Help", "Enable", "Disable" and "Remove" buttons should be greyed out in case the selection contains zero item. It is not useful to allow a 0-item selection; however, I think that in lists allowing multiple selection, it is not usual and maybe not easy to forbid an empty selection.

Describe alternatives you've considered

None

Additional context

N/A