Backend image rendering as plugin (#11966)

* rendering: headless chrome progress

* renderer: minor change

* grpc: version hell

* updated grpc libs

* wip: minor progess

* rendering: new image rendering plugin is starting to work

* feat: now phantomjs works as well and updated alerting to use new rendering service

* refactor: renamed renderer package and service to rendering to make renderer name less confusing (rendering is internal service that handles the renderer plugin now)

* rendering: now render key is passed and render auth is working in plugin mode

* removed unneeded lines from gitignore

* rendering: now plugin mode supports waiting for all panels to complete rendering

* fix: LastSeenAt fix for render calls, was not set which causes a lot of updates to Last Seen at during rendering, this should fix sqlite db locked issues in seen in previous releases

* change: changed render tz url parameter to use proper timezone name as chrome does not handle UTC offset TZ values

* fix: another update to tz param generation

* renderer: added http mode to renderer service, new ini setting [rendering] server_url

pkg/services/alerting/engine.go

@@ -12,11 +12,14 @@ import (
 	"github.com/benbjohnson/clock"
 	"github.com/grafana/grafana/pkg/log"
 	"github.com/grafana/grafana/pkg/registry"
+	"github.com/grafana/grafana/pkg/services/rendering"
 	"github.com/grafana/grafana/pkg/setting"
 	"golang.org/x/sync/errgroup"
 )
 
 type AlertingService struct {
+	RenderService rendering.Service `inject:""`
+
 	execQueue chan *Job
 	//clock         clock.Clock
 	ticker        *Ticker
@@ -48,7 +51,7 @@ func (e *AlertingService) Init() error {
 	e.evalHandler = NewEvalHandler()
 	e.ruleReader = NewRuleReader()
 	e.log = log.New("alerting.engine")
-	e.resultHandler = NewResultHandler()
+	e.resultHandler = NewResultHandler(e.RenderService)
 	return nil
 }