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/projection/projection.go

@@ -72,6 +72,8 @@ var (
 	QuotaProjection                     *quotaProjection
 	LimitsProjection                    *handler.Handler
 	RestrictionsProjection              *handler.Handler
+	SystemFeatureProjection             *handler.Handler
+	InstanceFeatureProjection           *handler.Handler
 )
 
 type projection interface {
@@ -148,6 +150,8 @@ func Create(ctx context.Context, sqlClient *database.DB, es handler.EventStore,
 	QuotaProjection = newQuotaProjection(ctx, applyCustomConfig(projectionConfig, config.Customizations["quotas"]))
 	LimitsProjection = newLimitsProjection(ctx, applyCustomConfig(projectionConfig, config.Customizations["limits"]))
 	RestrictionsProjection = newRestrictionsProjection(ctx, applyCustomConfig(projectionConfig, config.Customizations["restrictions"]))
+	SystemFeatureProjection = newSystemFeatureProjection(ctx, applyCustomConfig(projectionConfig, config.Customizations["system_features"]))
+	InstanceFeatureProjection = newInstanceFeatureProjection(ctx, applyCustomConfig(projectionConfig, config.Customizations["instance_features"]))
 	newProjectionsList()
 	return nil
 }
@@ -257,5 +261,7 @@ func newProjectionsList() {
 		QuotaProjection.handler,
 		LimitsProjection,
 		RestrictionsProjection,
+		SystemFeatureProjection,
+		InstanceFeatureProjection,
 	}
 }