PanelChrome: Use react Panel Header for angular panels. (#21265)

* WIP: Angular panel chrome, this is going to be tricky

* AngularPanelChrome: initial render works

* Options are showing up

* viz options working

* Fixed singlestat background

* AngularPanels: Fixed alert tab

* Removed anuglar loading spinner

* Dashboard: Refactor dashboard reducer & actions

* Dashboard: minor refactoring

* PanelChrome: loading state moved to header

* Subscribe to render events to solve title update issue

* Time info and query errors now works

* PanelHeader: unifying angular and react behavior

* added getPanelMenu test

* Scrollable now works again

* Various fixes

* Making stuff work

* seperate event emitter for angular

* Fixed issue sending updated dimensions to angular panel

* Minor tweaks

* Fixed tests

* Alerting: alert state now works

* Fixed unit tests

* Fixed a few null check errors

* Simplified events handling

* Fixed strict null checks

public/sass/components/_panel_header.scss

@@ -53,7 +53,7 @@ $panel-header-no-title-zindex: 1;
 }
 
 .panel-menu-container {
-  width: 1px;
+  width: 0px;
   height: 19px;
   display: inline-block;
 }

public/sass/components/_panel_table.scss

@@ -63,7 +63,7 @@
   }
 
   td {
-    padding: 0.45em 0 0.45em 1.1em;
+    padding: 0.45em 1.1em;
     border-bottom: 2px solid $body-bg;
     border-right: 2px solid $body-bg;