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/instance_by_domain.sql

@@ -0,0 +1,30 @@
+with domain as (
+	select instance_id from projections.instance_domains
+	where domain = $1
+), features as (
+	select instance_id, json_object_agg(
+		coalesce(i.key, s.key),
+		coalesce(i.value, s.value)
+	) features
+	from domain d
+	cross join projections.system_features s
+	full outer join projections.instance_features i using (key, instance_id)
+	group by instance_id
+)
+select
+    i.id,
+    i.default_org_id,
+    i.iam_project_id,
+    i.console_client_id,
+    i.console_app_id,
+    i.default_language,
+    s.enabled,
+    s.origins,
+    l.audit_log_retention,
+    l.block,
+	f.features
+from domain d
+join projections.instances i on i.id = d.instance_id
+left join projections.security_policies s on i.id = s.instance_id
+left join projections.limits l on i.id = l.instance_id
+left join features f on i.id = f.instance_id;