"Is recipient ready" for internal messaging

[grod220]

A follow up from #279 (comment). In short, we want to avoid having to set an arbitrary sleep on the service worker when making an internal request: https://github.com/penumbra-zone/web/pull/279/files#diff-1551d3677b3d0b691a3d8e4a29da867b3c0911786c1ab62528cf5e6dd11a5bdcR43-R47.

At the moment, internal extension messaging requires three steps (popup example):

1. Spawn popup window
2. Wait 500ms while React boots up
3. Send a message to the service

Some ideas discussed to explore:

• Create window returns a tabs object: https://developer.chrome.com/docs/extensions/reference/api/tabs#type-TabStatus. Not quite sure what "complete" means, but perhaps this means the document+javascript is loaded? If so, we can just poll chrome.tabs.get() until it's ready.
• Have the popup communicate ready. Would require something like (or alternatively, using listeners+ports):
  • Service worker:
    • in handler, store promise+request id in external object
    • route for accepting "ready" messages + ids and resolving those promises
  • Popup:
    • Take query param with request id and issue message to service worker indicating readiness

=====

From @jessepinho

• Explore async rendering of react for possible solution
• Have react render quicker (container & renderer method)

[turbocrime]

i think applying #310 to extension popup routes could provide benefit here, we could easily configure very early document behavior like attaching listeners and emitting ready events, and keep that state maintained as the react app stands up

[grod220]

Solving this will solve for prax-wallet/prax#130 as well