Add support for warnings when using APIs not compatible with min supported version

[manodasanW]

Created based on #283

Will this nuget package also include warnings when using an api that you need to feature-check on older builds?

We should look at if we can achieve this using a Roslyn analyzer that takes a input of the supported Windows versions.

[hansmbakker]

There is a relevant analyzer in the community toolkit but currently it is outdated and @michael-hawker suggested that another place might be better for it

[michael-hawker]

Thanks @hansmbakker for calling out the toolkit. This has been a big challenge for us, it was a great initial idea, but we soon realized the data isn't exposed to easily help a developer with analyzers based on their project settings. I think it's an unsupported scenario, which makes it difficult for us to provide value.

I don't know if this is something the CsWinRT folks can help with? If so great. It'd be great to just see this natively supported in VS as I think we can't go anywhere with our current analyzer?

[AdamBraden]

related to #411

[stevenbrix]

@manodasanW is this going to be different from #411? My understanding is that the .NET SDK will provide the analyzers if you are using the SupportedOSPlatformVersion property (equivalent to our TargetPlatformMinVersion property that exists today), along with those attributes.

See https://github.com/dotnet/designs/blob/main/accepted/2020/net5/net5.md#mapping-to-properties

[Scottj1s]

looks like a dupe of #411