* tag selector focus edits
- no tabstop on the tag selector scrollable area
- change tag selector's role from default "grid" to "group".
"grid" is not quite correct semantically and leads to
voiceover suggesting irrelevant commands.
- move all keyboard handling logic to tagSelectorList.jsx.
Tabbing through tag selector is now handled in ZoteroPane,
so the only logic left there is arrow navigation
between tags, and there's no reason to not have it
together with the tags list.
- a workaround to deal with focused tags when windowing
kicks in. When a tag is focused, record its index.
Each time tags are re-rendered, if the saved index is not
among rendered tags, refocus it, otherwise, move focus
to the tags list.
2835d6fe83