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

vendor/github.com/lib/pq/error.go

@@ -460,6 +460,11 @@ func errorf(s string, args ...interface{}) {
 	panic(fmt.Errorf("pq: %s", fmt.Sprintf(s, args...)))
 }
 
+// TODO(ainar-g) Rename to errorf after removing panics.
+func fmterrorf(s string, args ...interface{}) error {
+	return fmt.Errorf("pq: %s", fmt.Sprintf(s, args...))
+}
+
 func errRecoverNoErrBadConn(err *error) {
 	e := recover()
 	if e == nil {
@@ -488,7 +493,8 @@ func (c *conn) errRecover(err *error) {
 			*err = v
 		}
 	case *net.OpError:
-		*err = driver.ErrBadConn
+		c.bad = true
+		*err = v
 	case error:
 		if v == io.EOF || v.(error).Error() == "remote error: handshake failure" {
 			*err = driver.ErrBadConn