Recognize the old prefs URI as a defaultSettingsResource, to prevent an error when upgrading with the settings editor in history

For line comment, always use start line of language when falling back to block comments

Upstream PR: sourcelair/xterm.js#1072

Fixes #36560

With > 1 folder ctrl+shift+tilde will show the selector now

Fixes #34163

Includes letterSpacing/rendering coord clean up and .xterm class change

Fixes #36599

Fixes #36473

Fixes #2635

* Prototype TS Codefix commands

Initial prototype to support commands on JS/TS quick fixes

Part of #34787

* use command for argument name

* Update to use published api

fixes #36486