Generating resx files is broken

[natemcmaster]

As a result of #10674, the /t:Resx target is missing from projects.

To fix this, we need to set <GenerateResxSource>true</GenerateResxSource> to take advantage of Arcade's RESX feature, and delete the .Designer.cs files from source.

[natemcmaster]

See https://github.com/dotnet/arcade/blob/master/Documentation/ArcadeSdk.md#generateresxsource-bool

We should probably also set <GenerateResxSourceEmitFormatMethods>true</GenerateResxSourceEmitFormatMethods>

[JunTaoLuo]

FYI, some repos won't be able to convert due to: dotnet/arcade#3244.