Change tool TFMs to net6.0 and drop 3.1 hosting support

[hoyosjs]

This change:

• Moves tools and single file deployments to net6.0. Single-file deployments continue to be self-extracting
• Drops hosting support on net3.1 officially on managed tools.
• Removes 3.1 testing altogether.
• Adds native shim for ARM64 macOS. (Fixes Please offer native version for macOS Arm64 #3494)

[hoyosjs]

cc: @dotnet/dotnet-monitor

Also @dotnet/source-build-contrib, is adding ref packs to prebuilts expected? That means that every SDK update this will need an update.

[ghost]

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[oleksandr-didyk]

cc: @dotnet/dotnet-monitor

Also @dotnet/source-build-contrib, is adding ref packs to prebuilts expected? That means that every SDK update this will need an update.

If I understood your question correctly, you wanted to add the ref packs as exceptions to the baseline file? If so, then the answer is no - ideally we do not want to add any exceptions unless there is a strong reason to do this. Normally any new pre-built should be resolved by utilizing latest versions or any of the methods described in the prebuilt docs