Rework RAPPS to use WinGet manifests, add packages sources, add CLI tool

Currently, RAPPS uses ini-based manifests stored on a repo on our GitHub. This works but is custom for us and there's no tooling developed by others for managing or interfacing with it.

Starting with Windows 10 1809, Microsoft included the WinGet package manager with Windows. WinGet package sources also utilize manifests stored in a folder but are in yaml format. WinGet also supports adding custom repo sources and alternate or supplemental WinGet sources have been developed (for example, in corporate environments). The WinGet community package list is available here: https://github.com/microsoft/winget-pkgs

I want to move towards using WinGet compatible manifests for our package manager. Once we have switched over, I would like to add the ability to add additional repo sources to RAPPS, and when/if feasible, import the WinGet CLI tool.