backend/services: Move GetDashboard from sqlstore to dashboard service (#48971)

* rename folder to match package name
* backend/sqlstore: move GetDashboard into DashboardService

This is a stepping-stone commit which copies the GetDashboard function - which lets us remove the sqlstore from the interfaces in dashboards - without changing any other callers.
* checkpoint: moving GetDashboard calls into dashboard service
* finish refactoring api tests for dashboardService.GetDashboard

pkg/api/dashboard_permission_test.go

@@ -15,7 +15,7 @@ import (
 	"github.com/grafana/grafana/pkg/models"
 	accesscontrolmock "github.com/grafana/grafana/pkg/services/accesscontrol/mock"
 	"github.com/grafana/grafana/pkg/services/dashboards"
-	dashboardservice "github.com/grafana/grafana/pkg/services/dashboards/manager"
+	dashboardservice "github.com/grafana/grafana/pkg/services/dashboards/service"
 	"github.com/grafana/grafana/pkg/services/featuremgmt"
 	"github.com/grafana/grafana/pkg/services/guardian"
 	"github.com/grafana/grafana/pkg/services/sqlstore/mockstore"
@@ -26,6 +26,7 @@ func TestDashboardPermissionAPIEndpoint(t *testing.T) {
 	t.Run("Dashboard permissions test", func(t *testing.T) {
 		settings := setting.NewCfg()
 		dashboardStore := &dashboards.FakeDashboardStore{}
+		dashboardStore.On("GetDashboard", mock.Anything, mock.AnythingOfType("*models.GetDashboardQuery")).Return(nil)
 		defer dashboardStore.AssertExpectations(t)
 
 		features := featuremgmt.WithFeatures()