In order to launch UWP applications, we need to use a win32 native API:

https://github.com/flutter/flutter/pull/79684/files#diff-c87c94e076dd721f425a1061bd7c9d9be35ceb0e24963b559021b717ae27994cR17

This would be the only usage of ffi/win32 in the tool. Since the tool is not really set up to test this usage, we could instead build a C/C++ program in the engine which provides a command line application to launch apps, similar to the libimobile device tools.

This could be more easily tested in the engine, and the tool could depend on it like it does the existing prebuilts.

Example:

uwp_launcher launch SOME-ID ARGS

@cbracken @clarkezone