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/integration/client.go

@@ -27,6 +27,7 @@ import (
 	"github.com/zitadel/zitadel/pkg/grpc/admin"
 	"github.com/zitadel/zitadel/pkg/grpc/auth"
 	execution "github.com/zitadel/zitadel/pkg/grpc/execution/v3alpha"
+	feature "github.com/zitadel/zitadel/pkg/grpc/feature/v2beta"
 	mgmt "github.com/zitadel/zitadel/pkg/grpc/management"
 	object "github.com/zitadel/zitadel/pkg/grpc/object/v2beta"
 	oidc_pb "github.com/zitadel/zitadel/pkg/grpc/oidc/v2beta"
@@ -49,6 +50,7 @@ type Client struct {
 	OrgV2       organisation.OrganizationServiceClient
 	System      system.SystemServiceClient
 	ExecutionV3 execution.ExecutionServiceClient
+	FeatureV2   feature.FeatureServiceClient
 }
 
 func newClient(cc *grpc.ClientConn) Client {
@@ -63,6 +65,7 @@ func newClient(cc *grpc.ClientConn) Client {
 		OrgV2:       organisation.NewOrganizationServiceClient(cc),
 		System:      system.NewSystemServiceClient(cc),
 		ExecutionV3: execution.NewExecutionServiceClient(cc),
+		FeatureV2:   feature.NewFeatureServiceClient(cc),
 	}
 }