some refacto, doc fixes and jsx queries

- compute query language extensions *after* default ones
(jsx after javascript)
- remove outdated ts_utils functions from docs
- add better regex detection to javascript
- javascriptreact to use javascript queries
- add javascript.jsx to javascript queries
- write jsx.scm hl file

queries/javascript/highlights.scm

@@ -103,7 +103,8 @@
 (null) @constant.builtin
 (comment) @comment
 (string) @string
-(regex) @string.special
+(regex) @punctuation.delimiter
+(regex_pattern) @string.regex
 (template_string) @string
 (number) @number