Because Java comment syntax is not valid in Markdown.

**bug**
Indented lists in markdown stop highlighting after four indents, even if they are nested.

**Fix**
Allow lists to also match the start of the line instead of the anchor point in their while clause. This ensure that each list element can consume up to three spaces at each level.

* Add rule for html comment in blocks

* Match common mark spec for html comments

* Updating tests and fixing some token names

* Fix style and script blocks

* Fix test file results

* Fixed markdown tests for new html logic

fixes #14649

fixes #15165

Fixes #14661: `embeddedLanguages` is now scoped to the contribution point (i.e. it is not applied for all grammars)