feat: add debug events API (#8533)

# Which Problems Are Solved

Add a debug API which allows pushing a set of events to be reduced in a
dedicated projection.
The events can carry a sleep duration which simulates a slow query
during projection handling.

# How the Problems Are Solved

- `CreateDebugEvents` allows pushing multiple events which simulate the
lifecycle of a resource. Each event has a `projectionSleep` field, which
issues a `pg_sleep()` statement query in the projection handler :
  - Add
  - Change
  - Remove
- `ListDebugEventsStates` list the current state of the projection,
optionally with a Trigger
- `GetDebugEventsStateByID` get the current state of the aggregate ID in
the projection, optionally with a Trigger


# Additional Changes

- none

# Additional Context

-  Allows reproduction of https://github.com/zitadel/zitadel/issues/8517

internal/domain/debug_events.go

@@ -0,0 +1,14 @@
+package domain
+
+type DebugEventsState int
+
+const (
+	DebugEventsStateUnspecified DebugEventsState = iota
+	DebugEventsStateInitial
+	DebugEventsStateChanged
+	DebugEventsStateRemoved
+)
+
+func (state DebugEventsState) Exists() bool {
+	return state == DebugEventsStateInitial || state == DebugEventsStateChanged
+}