test: add sink functionality for idp intents (#9116)

# Which Problems Are Solved

New integration tests can't use command side to simulate successful
intents.

# How the Problems Are Solved

Add endpoints to only in integration tests available sink to create
already successful intents.

# Additional Changes

None

# Additional Context

Closes #8557

---------

Co-authored-by: Livio Spring <livio.a@gmail.com>

internal/integration/sink/stub.go

@@ -2,8 +2,10 @@
 
 package sink
 
+import "github.com/zitadel/zitadel/internal/command"
+
 // StartServer and its returned close function are a no-op
 // when the `integration` build tag is disabled.
-func StartServer() (close func()) {
+func StartServer(cmd *command.Commands) (close func()) {
 	return func() {}
 }