fix(permissions_v2): add membership fields migration (#9199)

# Which Problems Are Solved

Memberships did not have a fields table fill migration.

# How the Problems Are Solved

Add filling of membership fields to the repeatable steps.

# Additional Changes

- Use the same repeatable step for multiple fill fields handlers.
- Fix an error for PostgreSQL 15 where a subquery in a `FROM` clause
needs an alias ing the `permitted_orgs` function.

# Additional Context

- Part of https://github.com/zitadel/zitadel/issues/9188
- Introduced in https://github.com/zitadel/zitadel/pull/9152

internal/eventstore/handler/v2/field_handler.go

@@ -32,6 +32,9 @@ func (f *fieldProjection) Reducers() []AggregateReducer {
 
 var _ Projection = (*fieldProjection)(nil)
 
+// NewFieldHandler returns a projection handler which backfills the `eventstore.fields` table with historic events which
+// might have existed before they had and Field Operations defined.
+// The events are filtered by the mapped aggregate types and each event type for that aggregate.
 func NewFieldHandler(config *Config, name string, eventTypes map[eventstore.AggregateType][]eventstore.EventType) *FieldHandler {
 	return &FieldHandler{
 		Handler: Handler{
@@ -51,6 +54,7 @@ func NewFieldHandler(config *Config, name string, eventTypes map[eventstore.Aggr
 	}
 }
 
+// Trigger executes the backfill job of events for the instance currently in the context.
 func (h *FieldHandler) Trigger(ctx context.Context, opts ...TriggerOpt) (err error) {
 	config := new(triggerConfig)
 	for _, opt := range opts {