Crons: Monitor Assignment

[gaprl]

### Tasks
- [ ] https://github.com/getsentry/sentry/issues/68623
- [ ] https://github.com/getsentry/sentry/issues/68807
- [ ] https://github.com/getsentry/sentry/issues/69500
- [ ] https://github.com/getsentry/sentry-docs/pull/9784
- [ ] https://github.com/getsentry/develop/pull/1249
- [ ] https://github.com/getsentry/sentry/pull/69522
- [ ] https://github.com/getsentry/sentry/pull/69521
- [ ] Update SDKs to support owner

[evanpurkhiser]

@gaprl I'm not sure what upsert assignment is going to look like.

Right now the form that we use is user:<id> I don't think we should force users to have to lookup their IDs if we're going to allow upserting with ownership, we probably want to use email or teams. In which case, we'll probably need some kind of special processing here.

cc @wedamija for visibility here

[wedamija]

@gaprl I'm not sure what upsert assignment is going to look like.

Right now the form that we use is user:<id> I don't think we should force users to have to lookup their IDs if we're going to allow upserting with ownership, we probably want to use email or teams. In which case, we'll probably need some kind of special processing here.

cc @wedamija for visibility here

They can use user:email or something like that, and then we translate it to a user.