Refactor HUD to TypeScript/React (or Preact)

[davidkpiano]

As discussed with @avanderhoorn, the HUD's codebase needs to be refactored into a framework (React, can switch out for Preact for file savings) in order to alleviate maintenance concerns. This should ideally be done before any more features are added, so as to refactor it before it gets too complex (and it might already be past this point).

This will also put it on par with the tools/framework/libraries used in Glimpse.Client, which will make sharing components/business logic easier, as well as make the HUD more testable using Jest. Currently, there are no unit tests at all for the HUD (it is not trivial to test the code in its current state).