Add activation event for HTML

[Michael-Overall]

Add an onLanguage activation event to package.json as described here

Since VS Code lazy loads its extensions, this extension will need to be loaded when VS Code detects html files.

[Michael-Overall]

Additional complexity to this problem: we detect the file to fire up the extension (as described above), but the extension itself would need a listener for mic input and record/stream the input only when someone talks into the mic.