toolbar: disable buttons according to permissions (#2335)

* Closes #2327

Author: oliver-sanders

changes.d/2335.fix.md

@@ -0,0 +1 @@
+The play, pause and stop buttons in the workspace toolbar will now "grey out" if you do not have the permissions to run these commands.

src/components/cylc/workspace/Toolbar.vue

@@ -387,6 +387,7 @@ export default {
       return {
         playToggle: (
           // the play button (for the play from stopped scenario)
+          this.user.permissions.includes('play') &&
           this.isStopped &&
           (
             this.expecting.play === null ||
@@ -395,6 +396,10 @@ export default {
         ),
         pauseToggle: (
           // the play/pause button
+          (
+            (this.isPaused && this.user.permissions.includes('resume')) ||
+            (!this.isPaused && this.user.permissions.includes('pause'))
+          ) &&
           !this.isStopped &&
           !this.expecting.stop &&
           this.currentWorkflow.node.status !== WorkflowState.STOPPING.name &&
@@ -405,6 +410,7 @@ export default {
         ),
         stopToggle: (
           // the stop button
+          this.user.permissions.includes('stop') &&
           !this.isStopped &&
           (
             this.expecting.stop === null ||