✨ Draw Invisibles Only On Selection

### Description Some editors allow users to only see invisible characters in their selected text. Right now, CETV can only enable them for the entire document, or not at all. ### Alternatives Considered _No response_ ### Additional Context Some updated requirements: - The line fragment renderer will need to know about selected ranges, this introduces an interesting dependency tree. - Querying selected ranges may be slow when it's done for *every* visible line fragment each render loop. The implementation should consider this or profile it to make sure it's negligible. ### Screenshots _No response_