Plugins: Refactor plugin dashboards (#44315)

Moves/refactor Grafana specific functionality related to plugin dashboards 
out to specific services for importing dashboards and keep app plugin dashboards
up-to-date.

Fixes #44257

pkg/web/webtest/webtest_test.go

@@ -0,0 +1,66 @@
+package webtest
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"testing"
+
+	"github.com/grafana/grafana/pkg/api/response"
+	"github.com/grafana/grafana/pkg/api/routing"
+	"github.com/grafana/grafana/pkg/models"
+	"github.com/stretchr/testify/require"
+)
+
+func TestServerClient(t *testing.T) {
+	routeRegister := routing.NewRouteRegister()
+	routeRegister.Get("/test", routing.Wrap(func(c *models.ReqContext) response.Response {
+		return response.JSON(http.StatusOK, c.SignedInUser)
+	}))
+
+	s := NewServer(t, routeRegister)
+
+	t.Run("Making a request with user 1 should return user 1 as signed in user", func(t *testing.T) {
+		req := s.NewRequest(http.MethodGet, "/test", nil)
+		req = RequestWithWebContext(req, &models.ReqContext{
+			SignedInUser: &models.SignedInUser{
+				UserId: 1,
+			},
+		})
+		resp, err := s.Send(req)
+		require.NoError(t, err)
+		require.NotNil(t, resp)
+		require.Equal(t, http.StatusOK, resp.StatusCode)
+		bytes, err := ioutil.ReadAll(resp.Body)
+		require.NoError(t, err)
+		require.NoError(t, resp.Body.Close())
+
+		var user *models.SignedInUser
+		err = json.Unmarshal(bytes, &user)
+		require.NoError(t, err)
+		require.NotNil(t, user)
+		require.Equal(t, int64(1), user.UserId)
+	})
+
+	t.Run("Making a request with user 2 should return user 2 as signed in user", func(t *testing.T) {
+		req := s.NewRequest(http.MethodGet, "/test", nil)
+		req = RequestWithWebContext(req, &models.ReqContext{
+			SignedInUser: &models.SignedInUser{
+				UserId: 2,
+			},
+		})
+		resp, err := s.Send(req)
+		require.NoError(t, err)
+		require.NotNil(t, resp)
+		require.Equal(t, http.StatusOK, resp.StatusCode)
+		bytes, err := ioutil.ReadAll(resp.Body)
+		require.NoError(t, err)
+		require.NoError(t, resp.Body.Close())
+
+		var user *models.SignedInUser
+		err = json.Unmarshal(bytes, &user)
+		require.NoError(t, err)
+		require.NotNil(t, user)
+		require.Equal(t, int64(2), user.UserId)
+	})
+}