Remove unsupported solution configs, make get_testwinrt curdir-independent, assert TestWinRT requirement

[Scottj1s]

fixes #692

[j0shuams]

I see we are removing Arm and Arm64 -- when I was doing nuget work I know I made sure we included these host dlls. But only if they exist, which made me think eventually we will make these to support arm architectures. I see we are removing those platforms, is the plan to add support for arm{64} in the future or are we sticking with x86/x64?

[Scottj1s]

I see we are removing Arm and Arm64 -- when I was doing nuget work I know I made sure we included these host dlls. But only if they exist, which made me think eventually we will make these to support arm architectures. I see we are removing those platforms, is the plan to add support for arm{64} in the future or are we sticking with x86/x64?

No plans to ever build a cswinrt.exe (or other native components) for ARM32/64. Removing those configs, and Any CPU, prevents confusion for devs when they open the sln

[j0shuams]

I see we are removing Arm and Arm64 -- when I was doing nuget work I know I made sure we included these host dlls. But only if they exist, which made me think eventually we will make these to support arm architectures. I see we are removing those platforms, is the plan to add support for arm{64} in the future or are we sticking with x86/x64?

No plans to ever build a cswinrt.exe (or other native components) for ARM32/64. Removing those configs, and Any CPU, prevents confusion for devs when they open the sln

Does this mean we should update our nuget pipeline / build cmd to not consider winrt.host dlls for arm architectures?

[manodasanW]

Opened #708 to track ARM64 support for WinRT.Host.