Support explicit architecture for dotnet

[ww898]

Description:
I need to install both arm64 and x64 architectures for .NET 8.0 on macOS M1 for execute tests on different platforms. Now it checks only arm64 version and say that everything was already installed.

Justification:
Example of the new symtax:

        uses: actions/setup-dotnet@v4
        with:
          dotnet:
            - version: 8.0.x
               arch: x64
            - version: 8.0.x
               arch: arm64

[aparnajyothi-y]

Hello @ww898, Thank you for creating the feature request and we will get back to you once we have some feedback on this :)