[Scheduled Actions] CHASM API Handlers

[lina-temporal]

What changed?

• Added an RPC service to the CHASM Scheduler which implements its CRUD operations.
• The intention is for the frontend handler to attempt to route to CHASM
  operations in history, and in the event of a not-found, let frontend retry its
  old (V1 scheduler) path.
• These assume frontend's validation. As we move towards ripping out the old
  scheduler code, we'll start moving all of that existing logic over into the CHASM
  world, but for now, let's keep it as-is for as light a possible touch on existing
  paths.
• This is based on standalone-activity just to get the API boilerplate stuff.