Improve JavaScript and TypeScript syntax highlighting

[chbk]

Release Notes:

• Improved JavaScript and TypeScript syntax highlighting.

Zed 0.174.6	With this PR

• regex_flags: keyword.regex, see the Regex PR for other Regex scopes
• @: punctuation.special, as in Python
• jsx_text: text.jsx
• =: operator -> punctuation.jsx.delimiter, punctuation as in VS Code and Atom
• added jsx scope to target JSX tokens specifically

/**
 * @keyword comment
 */
@log
class X {
  render() {
    return (
      <div jsx_attribute="value">
        <Input onKeyPress={super.bind(this)}/>
        jsx_text
      </div>
    );
  }
}
const IDENTIFIER = true

[maxdeviant]

Thank you!