Add F#

[purkhusid]

What?

This PR adds the following:

• Updates rules_dotnet to the latest commit for .Net 5.0 support
• Adds F# Protobuf/gRPC support using https://github.com/Arshia001/FSharp.GrpcCodeGenerator
• Adds Routeguide example for F#

[purkhusid]

This is ready for review

[aaliddell]

Wow, awesome! I'll take a look at this on the weekend or sooner if I get a chance.

I still need to get back to you on platforms/toolchains topic on rules_dotnet, but I need to make a demo repo to check it

[purkhusid]

awesome! I'll take a look at this on the weekend or sooner if I get a chance.

I still need to get back to you on platforms/toolchains topic on rules_dotnet, but I need to make a demo repo to check it

Sounds great! I would love to find a way to configure rules_dotnet without platform flags that also works with target_compatible_with

[aaliddell]

Merging into dev in advance of 3.2.0. Thanks!