Follow up task for named runtime pack functionality

[steveisok]

In #34980, we are overriding the name of Microsoft.NETCore.App.Runtime.{RID}.{version}.nupkg with Microsoft.NETCore.App.Runtime.Mono.{RID}.{version}.nupkg. This issue is follow up work to simplify what is being renamed.

• Change RidSpecificPackProperties to be <RidSpecificPackProperties>BaseId=$(MSBuildProjectName)$(RuntimeSpecificFrameworkSuffix).$(PackageBuildRID);IdPrefix=</RidSpecificPackProperties> Update RidSpecificPackProperties in framework.packing.targets arcade#5287
• Remove MobileGetBuildRidSpecificPackageProps target and create a property group RuntimeSpecificFrameworkSuffix with .Mono inside. [installer] Add RuntimeSpecificFrameworkSuffix property #35124

The end result should be the same. A Microsoft.NETCore.App.Runtime.Mono.{RID}.{version}.nupkg produced for desktop mono builds.

[dagood]

• Alter the MobileGetBuildRidSpecificPackageProps target to override RuntimeSpecificFrameworkSuffix with .Mono

Shouldn't need a target. Copying my suggestion from #34980 (comment) to make it easy to reach:

this should be done with a small tweak over here (but without the redundant .Mono):

https://github.com/dotnet/arcade/blob/be7971c98d4ad60cdf8c3d1aa41f950f42bd466a/src/Microsoft.DotNet.Build.Tasks.SharedFramework.Sdk/targets/framework.packaging.targets#L224

<RidSpecificPackProperties>BaseId=$(MSBuildProjectName)$(RuntimeSpecificFrameworkSuffix).$(PackageBuildRID);IdPrefix=</RidSpecificPackProperties>

And you'd use that API here in dotnet/runtime by specifying the property:

<PropertyGroup Condition="'$(RuntimeFlavor)' == 'Mono' and '$(TargetsMobile)' != 'true'">
  <RuntimeSpecificFrameworkSuffix>.Mono</RuntimeSpecificFrameworkSuffix>
</PropertyGroup>

[dagood]

we are overriding the name of Microsoft.NETCore.App.Runtime with Microsoft.NETCore.App.Mono.Runtime.

Not quite: Microsoft.NETCore.App.Runtime.Mono.{RID}.{version}.nupkg

This corresponds to BaseId=$(MSBuildProjectName)$(RuntimeSpecificFrameworkSuffix).$(PackageBuildRID)