diagnostics for queries & parse-tree editor#7

implements diagnostics for - typescript files -- the template string within `treeSitterQuery.<language>` template string formatting function is checked for - query files .scm with the top line being a comment containing language, e.g., `;; typescript` (works for notebook cells as well but still requires top comment) ---- add command "Open Parse Tree View to the Side" : implements a parse-tree viewer using a webview (clicking on a parse-tree node highlights corresponding range in the original file, but doesn't work the other way around) ---- I hope to address limitations above in further PRs when I have more time