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/eventstore/handler/v2/statement.go

@@ -338,6 +338,21 @@ func NewNoOpStatement(event eventstore.Event) *Statement {
 	return NewStatement(event, nil)
 }
 
+func NewSleepStatement(event eventstore.Event, d time.Duration, opts ...execOption) *Statement {
+	return NewStatement(
+		event,
+		exec(
+			execConfig{
+				args: []any{float64(d) / float64(time.Second)},
+			},
+			func(_ execConfig) string {
+				return "SELECT pg_sleep($1);"
+			},
+			opts,
+		),
+	)
+}
+
 func NewMultiStatement(event eventstore.Event, opts ...func(eventstore.Event) Exec) *Statement {
 	if len(opts) == 0 {
 		return NewNoOpStatement(event)
@@ -385,6 +400,12 @@ func AddCopyStatement(conflict, from, to []Column, conditions []NamespacedCondit
 	}
 }
 
+func AddSleepStatement(d time.Duration, opts ...execOption) func(eventstore.Event) Exec {
+	return func(event eventstore.Event) Exec {
+		return NewSleepStatement(event, d, opts...).Execute
+	}
+}
+
 func NewArrayAppendCol(column string, value interface{}) Column {
 	return Column{
 		Name:  column,