Core: KivyMD and Launcher overhaul (#3934)

Shifts the contents of `kvui.py`, and thus all CommonClient-based clients as well as Launcher, to using KivyMD. KivyMD is an extension for Kivy that is almost fully compatible with pre-existing Kivy components, while providing Material Design support for theming and overall visual design as well as useful pre-existing built in components such as Snackbars, Tooltips, and a built-in File Manager (not currently being used).

As a part of this shift, the launcher was completely overhauled, adding the ability to filter the list of components down to each type of component, the ability to define favorite components and filter to them, and add shortcuts for launcher components to the desktop. An optional description field was added to Component for display within the new launcher.

The theme (Light/Dark) and primary palette have also been exposed to users via client/user.kv.

WargrooveClient.py

@@ -214,17 +214,11 @@ class WargrooveContext(CommonContext):
     def run_gui(self):
         """Import kivy UI system and start running it as self.ui_task."""
         from kvui import GameManager, HoverBehavior, ServerToolTip
-        from kivy.uix.tabbedpanel import TabbedPanelItem
+        from kivymd.uix.tab import MDTabsItem, MDTabsItemText
         from kivy.lang import Builder
-        from kivy.uix.button import Button
         from kivy.uix.togglebutton import ToggleButton
         from kivy.uix.boxlayout import BoxLayout
-        from kivy.uix.gridlayout import GridLayout
-        from kivy.uix.image import AsyncImage, Image
-        from kivy.uix.stacklayout import StackLayout
         from kivy.uix.label import Label
-        from kivy.properties import ColorProperty
-        from kivy.uix.image import Image
         import pkgutil
 
         class TrackerLayout(BoxLayout):