Core: KivyMD and Launcher overhaul

[Silvris]

What is this fixing or adding?

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.

How was this tested?

Manually, across the span of numerous unsupported games. I'm considering putting out a pre-release version for wider testing as well.

The Launcher changes were tested manually, both in a frozen build and on source.

If this makes graphical changes, please attach screenshots.

Launcher - Dark/Green

Launcher - Light/Lavenderblush

Launcher - Dark/Violet

Text Client - Dark/Red

Text Client - Dark/Cyan