Validate IReminderTable during startup if any grains implement IRemindable

[ReubenBond]

Fixes #4278

This assumes that if the user adds some grain which implements IRemindable, then that means they intend to use reminders. That assumption might not be true, but maybe we'll decide it's better to err on the side of caution.

An alternative is late checking, like so:

I'm happy with either and looking for input.

[ReubenBond]

@dotnet-bot test functional

UnitTests.ActivationsLifeCycleTests.DeactivateOnIdleTests.DeactivateOnIdle_NonExistentActivation_1
MESSAGE:
Orleans.Runtime.OrleansLifecycleCanceledException : Lifecycle start canceled due to errors at stage 20000\r\n---- Orleans.Runtime.OrleansMessageRejectionException : Forwarding failed: tried to forward message NewPlacement Request S127.0.0.1:27756:259412658stg/0/00000000@S00000000->S127.0.0.1:27756:259412658grn/FCB3F509/00003039@a067ac8a #13: for 0 times after Duplicate activation to invalid activation. Rejecting now.

[ReubenBond]

Maybe we should table this approach and go for the lazy approach in the diff image above.

EDIT: opened #4287

[sergeybykov]

Let's close this one for now. The concern is that this might be too aggressive, and lead to unintended consequences in corner cases.