[Toolbar] set selection initially in fixed controller and toolbar... (#1994)

* [Toolbar] set selection initially in fixed controller and toolbar...

... to make the add button appear in the toolbar when a fixed position is created.

Remove selection change listener on destroy.

Start a digest cycle when handling selection in toolbar to avoid delays in toolbar.

Fixes #1991, #1987

* fixed checkstyle and lint errors

* Fix tests

* Update comment

platform/features/layout/src/FixedController.js

@@ -315,6 +315,8 @@ define(
             this.openmct.time.on("bounds", updateDisplayBounds);
             this.openmct.selection.on('change', setSelection);
             this.$element.on('click', this.bypassSelection.bind(this));
+
+            setSelection(this.openmct.selection.get());
         }
 
         /**

platform/features/layout/test/FixedControllerSpec.js

@@ -201,7 +201,7 @@ define(
                     'off',
                     'get'
                 ]);
-                mockSelection.get.andCallThrough();
+                mockSelection.get.andReturn([]);
 
                 mockOpenMCT = {
                     time: mockConductor,
@@ -596,7 +596,7 @@ define(
                 expect(controller.getSelectedElementStyle()).not.toEqual(oldStyle);
             });
 
-            it("cleans up slection on scope destroy", function () {
+            it("cleans up selection on scope destroy", function () {
                 expect(mockScope.$on).toHaveBeenCalledWith(
                     '$destroy',
                     jasmine.any(Function)