feat: get user scim v2 endpoint (#9161)

# Which Problems Are Solved
- Adds support for the get user SCIM v2 endpoint

# How the Problems Are Solved
- Adds support for the get user SCIM v2 endpoint under `GET
/scim/v2/{orgID}/Users/{id}`

# Additional Context
Part of #8140
Replaces https://github.com/zitadel/zitadel/pull/9154 as requested by
the maintainers, discussions see
https://github.com/zitadel/zitadel/pull/9154.

internal/api/scim/resources/resource_handler.go

@@ -20,6 +20,7 @@ type ResourceHandler[T ResourceHolder] interface {
 
 	Create(ctx context.Context, resource T) (T, error)
 	Delete(ctx context.Context, id string) error
+	Get(ctx context.Context, id string) (T, error)
 }
 
 type Resource struct {