Enable Grafana extensions at build time. (#11752)

* extensions: import and build

* bus: use predefined error

* enterprise: build script for enterprise packages

* poc: auto registering services and dependency injection

(cherry picked from commit b5b1ef875f905473af41e49f8071cb9028edc845)

* poc: backend services registry progress

(cherry picked from commit 97be69725881241bfbf1e7adf0e66801d6b0af3d)

* poc: minor update

(cherry picked from commit 03d7a6888b81403f458b94305792e075568f0794)

* ioc: introduce manuel ioc

* enterprise: adds setting for enterprise

* build: test and build specific ee commit

* cleanup: test testing code

* removes example hello service

pkg/registry/registry.go

@@ -0,0 +1,33 @@
+package registry
+
+import (
+	"context"
+)
+
+var services = []Service{}
+
+func RegisterService(srv Service) {
+	services = append(services, srv)
+}
+
+func GetServices() []Service {
+	return services
+}
+
+type Service interface {
+	Init() error
+}
+
+// Useful for alerting service
+type CanBeDisabled interface {
+	IsDisabled() bool
+}
+
+type BackgroundService interface {
+	Run(ctx context.Context) error
+}
+
+func IsDisabled(srv Service) bool {
+	canBeDisabled, ok := srv.(CanBeDisabled)
+	return ok && canBeDisabled.IsDisabled()
+}