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Fix markdown preview refresh command potentially resetting preview scroll position to top if focused on preview

Fixes #80680

This is needed to help us better understand which TS versions users have enabled in their workspaces

Based on telemetry, these versions have pretty much zero usage in the past 30 days. Removing the extra gating code since we can now assume users are on TS > 2.2.

Fixes #80656

Fix-79658 New pattern to Preserve Case ( underscore separated variables)

Fixes #80744

Refactor terminal ext host to move most to common/

* Fix bug causing a large number of linters to be activated due to the markdown extension opening TextDocuments during indexing

* indentation problem

* code review by @OmarTawfik

* revert changed file

* Code review: use nodejs' Buffer

* fix ineffcient code
code review comments

* introduce SkinnyTextLine

* refactor redundant code

* revert changed files

* formatting

* remove empty line

* add cansavecontextkey

* use save logic for save active editor ctx key

* use context key plus explorer focus

* remove unused imports

* feedback

Fix #80361