style: Rewrote app grid tile drawing functions

- updated mixin for tile_button
- dropped the overview_button mixin
- minor changes to dash, appDisplay and switcherPopup JS to accommodate new stylesheet
- new focus style for all tile buttons
- improved high contrast style support for app grid and dash
- renamed some style-classes
- tidied up dash stylesheet

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3017>

js/ui/appDisplay.js

@@ -2324,7 +2324,7 @@ export const FolderIcon = GObject.registerClass({
 }, class FolderIcon extends AppViewItem {
     _init(id, path, parentView) {
         super._init({
-            style_class: 'app-well-app app-folder',
+            style_class: 'overview-tile app-folder',
             button_mask: St.ButtonMask.ONE,
             toggle_mode: true,
             can_focus: true,
@@ -2992,7 +2992,7 @@ export const AppIcon = GObject.registerClass({
         const expandTitleOnHover = appIconParams['expandTitleOnHover'];
         delete iconParams['expandTitleOnHover'];
 
-        super._init({style_class: 'app-well-app'}, isDraggable, expandTitleOnHover);
+        super._init({style_class: 'overview-tile'}, isDraggable, expandTitleOnHover);
 
         this.app = app;
         this._id = app.get_id();
@@ -3014,13 +3014,14 @@ export const AppIcon = GObject.registerClass({
         this._iconContainer.add_child(this.icon);
 
         this._dot = new St.Widget({
-            style_class: 'app-well-app-running-dot',
+            style_class: 'app-grid-running-dot',
             layout_manager: new Clutter.BinLayout(),
             x_expand: true,
             y_expand: true,
             x_align: Clutter.ActorAlign.CENTER,
             y_align: Clutter.ActorAlign.END,
         });
+        this._dot.translationY = 8;
         this._iconContainer.add_child(this._dot);
 
         this.label_actor = this.icon.label;