Measure % of new apps using RNW+WinAppSDK

[asklar]

[chrisglein]

There may be some instrumentation in WinAppSDK itself that we can leverage. If that works for us, great. If not, this would go into the RNW CLI telemetry.

[asklar]

@chrisglein I believe the existing instrumentation is in VS for file->new project which wouldn't capture usage through since we don't use the winappsdk templates.