Tab browser keyboard shortcuts

Keyboard shortcuts for tabs:

[x] Mod-W to close tabs?
[x] ~~Mod-Left/Right to navigate between tabs? Mod-Tab?~~
[x] Add tab region to tab index
[x] Add correct ARIA roles to tab elements (Using automatic activation. See: https://www.w3.org/WAI/ARIA/apg/patterns/tabs/examples/tabs-automatic/)
[x] ~~Add visual indicator for when editor is in tab-trapped and non-tab-trapped mode~~
[x] Use different command (rather than Esc for showing/hiding console (probably Mod-`)
[x] Fix issue with keyboard not triggering close buttons

matthewkaney / text.management