Use CancellationToken for search

#34711 - run search for 5s, if it times out, activate the extension anyway

Fixes #36169

An option to copy only plain text to clipboard.

Do not auto-close when ending with open

Fixes #57209

Use providedCodeActionKinds to avoid calling providers that we know will not return actions of interest

Part of #57875

Ensure that a search with an immediately canceled token does not actually start a search. Fix possibly flaky findFiles test

Fixes #57542

Also make reader dispoable

Fixes #57534

Fix #57333 - consider "first visible element" to be the element with at least half its content visible

Part of #57680

fixes #57866