Add shortcuts to support vision impaired

[drorm]

As @freetimekate mentioned in C-Nedelcu/talk-to-chatgpt#25, voice apps can help folks who are vision impaired.

Provide shortcuts for:

Description	shortcut	mouse equivalent
Microphone listen/mute	CTRL - Space	Click on the microphone icon
Bot pause/resume speaking answer	CTRL-SHIFT-S	Click on "Ne Chat" top left
Bot stop speaking. abort answer	CTRL-SHIFT-A	Click on "Ne Chat" top left
New ChatGPT chat	TBD	Click on "Ne2 Chat" top left

Should we use the CTRL and SHIFT combinations above, or just use the bare keys: 'S', 'A', SPACE, etc. and require that the cursor not be in the typing textarea. That would make things simpler and avoid the possibility of conflicts with the browser (less of an issue since we only support Chrome) or the OS.

In C-Nedelcu/talk-to-chatgpt#25 (comment) there are some implementation suggestions, but we should also look at how screen readers currently handle things, and in general the state of online tools for the visually impaired.