all: Display fs watcher status and retry starting it (ref #4552) (#4713)

cmd/syncthing/mocked_model_test.go

@@ -136,3 +136,7 @@ func (m *mockedModel) UsageReportingStats(version int, preview bool) map[string]
 func (m *mockedModel) PullErrors(folder string) ([]model.FileError, error) {
 	return nil, nil
 }
+
+func (m *mockedModel) WatchError(folder string) error {
+	return nil
+}