[expressions] editor component

[streamich]

• Use advanced editor (e.g Monaco, CodeMirror, AceEditor).
• Implement language service with code completion and syntax highlighting.
• Support read-only mode, where user can only see the expression and hover its parts to see language service help tips.
• When expression has 1 or less lines, component collapses to one line and expands to more lines automatically as user types in more lines.

Canvas expression editor:

Splunk search language:

Parent issue: #46909

[elasticmachine]

Pinging @elastic/kibana-app-arch (Team:AppArch)

[ppisljar]

Thank you for contributing to this issue, however, we are closing this issue due to inactivity as part of a backlog grooming effort. If you believe this feature/bug should still be considered, please reopen with a comment.