feat(playground): Implement codemirror based template string editor (#4943)

* feat(playground): Implement codemirror based template string editor

* Implement mustacheLike Language grammar

* Fix top level language definitions

* feat(playground): Support template escaping and nesting in fstring template lang

* feat(playground): Improve mustache grammar and implement mustache format fn

* fix(playground): Allow Enter key within codemirror editor

* refactor(playground): Improve comments for mustache like lang

* refactor(playground): Refactor variable extraction and lang format funcs into shared utils

* test(playground): Test FStringTemplate and MustacheTemplate languages

* refactor(playground): Remove debug logging

* fix(playground): Correctly parse empty templates, escape slashes, triple braces

* fix(playground): Apply parsing fixes to fstring as well

* refactor(playground): Remove debug

* docs(playground): Add comments to lexer grammars

* docs(playground): Add comments to debug fns

* docs(playground): Improve comment formatting

* refactor(playground): Use named object arguments for variable extractor

* refactor(playground): rename lang directories

* fix(playground): Add a lightmode theme to template editor

* refactor(playground): More detailed typing to variable format record