feat(api): feature flags (#7356)

* feat(api): feature API proto definitions

* update proto based on discussion with @livio-a

* cleanup old feature flag stuff

* authz instance queries

* align defaults

* projection definitions

* define commands and event reducers

* implement system and instance setter APIs

* api getter implementation

* unit test repository package

* command unit tests

* unit test Get queries

* grpc converter unit tests

* migrate the V1 features

* migrate oidc to dynamic features

* projection unit test

* fix instance by host

* fix instance by id data type in sql

* fix linting errors

* add system projection test

* fix behavior inversion

* resolve proto file comments

* rename SystemDefaultLoginInstanceEventType to SystemLoginDefaultOrgEventType so it's consistent with the instance level event

* use write models and conditional set events

* system features integration tests

* instance features integration tests

* error on empty request

* documentation entry

* typo in feature.proto

* fix start unit tests

* solve linting error on key case switch

* remove system defaults after discussion with @eliobischof

* fix system feature projection

* resolve comments in defaults.yaml

---------

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

internal/query/system_features_model.go

@@ -0,0 +1,82 @@
+package query
+
+import (
+	"github.com/zitadel/zitadel/internal/eventstore"
+	"github.com/zitadel/zitadel/internal/feature"
+	"github.com/zitadel/zitadel/internal/repository/feature/feature_v2"
+)
+
+type SystemFeaturesReadModel struct {
+	*eventstore.ReadModel
+	system *SystemFeatures
+}
+
+func NewSystemFeaturesReadModel() *SystemFeaturesReadModel {
+	m := &SystemFeaturesReadModel{
+		ReadModel: &eventstore.ReadModel{
+			AggregateID:   "SYSTEM",
+			ResourceOwner: "SYSTEM",
+		},
+		system: new(SystemFeatures),
+	}
+	return m
+}
+
+func (m *SystemFeaturesReadModel) Reduce() error {
+	for _, event := range m.Events {
+		switch e := event.(type) {
+		case *feature_v2.ResetEvent:
+			m.reduceReset()
+		case *feature_v2.SetEvent[bool]:
+			err := m.reduceBoolFeature(e)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return m.ReadModel.Reduce()
+}
+
+func (m *SystemFeaturesReadModel) Query() *eventstore.SearchQueryBuilder {
+	return eventstore.NewSearchQueryBuilder(eventstore.ColumnsEvent).
+		AwaitOpenTransactions().
+		AddQuery().
+		AggregateTypes(feature_v2.AggregateType).
+		AggregateIDs(m.AggregateID).
+		EventTypes(
+			feature_v2.SystemResetEventType,
+			feature_v2.SystemLoginDefaultOrgEventType,
+			feature_v2.SystemTriggerIntrospectionProjectionsEventType,
+			feature_v2.SystemLegacyIntrospectionEventType,
+		).
+		Builder().ResourceOwner(m.ResourceOwner)
+}
+
+func (m *SystemFeaturesReadModel) reduceReset() {
+	m.system = new(SystemFeatures)
+}
+
+func (m *SystemFeaturesReadModel) reduceBoolFeature(event *feature_v2.SetEvent[bool]) error {
+	level, key, err := event.FeatureInfo()
+	if err != nil {
+		return err
+	}
+	var dst *FeatureSource[bool]
+
+	switch key {
+	case feature.KeyUnspecified:
+		return nil
+	case feature.KeyLoginDefaultOrg:
+		dst = &m.system.LoginDefaultOrg
+	case feature.KeyTriggerIntrospectionProjections:
+		dst = &m.system.TriggerIntrospectionProjections
+	case feature.KeyLegacyIntrospection:
+		dst = &m.system.LegacyIntrospection
+	}
+
+	*dst = FeatureSource[bool]{
+		Level: level,
+		Value: event.Value,
+	}
+	return nil
+}