Improve extensions build. (#12461)

* enable ee build on pr/master

* step1: of including group sync

* disable commit pinning for now

* fixes broken build

* enable team to ldap group sync

* avoid returning error for missing external handler

* services: allow routes to be added before http server start

* services: allows services to add their own migrations

* moves db migrations to ee code base

* build using master branch in ee

* disable enterprise build in .bra.toml

[skip ci]

* removes team sync extensions

* removes commented line

pkg/api/frontendsettings.go

@@ -132,6 +132,7 @@ func getFrontendSettingsMap(c *m.ReqContext) (map[string]interface{}, error) {
 	}
 
 	jsonObj := map[string]interface{}{
+		"enterprise":              setting.Enterprise,
 		"defaultDatasource":       defaultDatasource,
 		"datasources":             datasources,
 		"panels":                  panels,