Integrated terminal non-falsey shell exit codes should be reported to the UI, not just the console

Fixes #8553

Fixes #8319

Fixes #8402

This change also consistently hides the terminal when exiting the final
terminal.

Fixes #8211

Uses editor.cursorBlinking === 'blink'

Fixes #8085
Fixes #7616

Fixes #7670

Focus previous/next are temporary until tabs are visualized in the UI

Part of #6458

This fixes the right-portion of the screen not scrolling (where the lines don't reach)

Fixes #6743

Fixes #75

The character measure logic has been shuffled around a little and now is done
primarily in setVisible after the terminal is confirmed to be within the DOM.

Part of #6458

resolves #6728

Fixes #6791

Fixes #6726