AuthN: Add client to perform basic authentication (#60877)

* AuthN: Add basic auth client boilerplate

* AuthN: Implement test function for basic auth client

* AuthN: Implement the authentication method for basic auth

* AuthN: Add tests for basic auth authentication

* ContextHandler: perform basic auth authentication through authn service
if feature toggle is enabled

* AuthN: Add providers for sync services and pass required dependencies

pkg/services/authn/authnimpl/usersync/usersync.go

@@ -13,6 +13,10 @@ import (
 	"github.com/grafana/grafana/pkg/services/user"
 )
 
+func ProvideUserSync(userService user.Service, authInfoService login.AuthInfoService, quotaService quota.Service) *UserSync {
+	return &UserSync{userService, authInfoService, quotaService, log.New("user.sync")}
+}
+
 type UserSync struct {
 	userService     user.Service
 	authInfoService login.AuthInfoService