API proposal for COM\WinRT interface for Winget install

[sreadingMSFT]

The Windows Package Manager currently exposes a command line interface to search for packages, install them, view progress, and more. This proposal for a COM\WinRT API is designed to provide another way for callers to make use of that functionality. The COM\WinRT API will be preferred by callers that want to receive progress and completion events, and UWP packages that do not have permission to launch command line processes. The goal for this API is to provide the full set of install functionality possible using the Windows Package Manager command line.

A proposal for the API is in a draft pull request here:
#889

I'll be sharing that request out with the API design review team and will update here and in the pull request when that review has a scheduled date.