Add .Net 6 and ARM support

[jeremyosterhoudt]

• Added .Net 6.0 support
• Added the ability to build for architectures other than Intel/AMD (Apple Silicon included)

[sriv]

hi @jeremyosterhoudt Thank you for sending this PR, I am taking a look at the changeset. Please note that the commits need to be all signed-off in order for the Developer Certificate of Origin check to pass. You can see the details here: https://github.com/getgauge/gauge-dotnet/pull/174/checks?check_run_id=4734983252

[jeremyosterhoudt]

Thanks @sriv. I've signed the commit. I did have a question on whether to keep .Net 5 as a target? My initial feeling is it goes out of service support in March so must people should be migrating to .Net 6 for LTS. However, laggards won't be able to upgrade to this version who are sticking with .Net 5 targets.

I'm happy to add a 3rd target so .Net 5 and 6 will be targets if needed, but figured I would go with this simpler solution to start.

[sriv]

the check for LSP tests are failing, I'll get this sorted

[sriv]

The github actions workflow needs some love, the versions used are a bit dated. Feel free to play with it @jeremyosterhoudt if you have the time. It'll probably take me at least a couple of days to be able to get to it .