CoreCLR: tell the R2R/NAOT compiler which instruction set an app requires/support

[rolfbjarne]

Ref: dotnet/runtime#122249

To enable usage of newer instructions in native code, we should implement support for computing the minimum/oldest CPU / instruction set an app requires based on the deployment target (min supported os version), and passing this info along to the R2R/NAOT compiler.

See also: https://teams.microsoft.com/l/chat/19:ea31bce2f4da4abd977f4b4544e6dedd@thread.v2/conversations?context=%7B%22contextType%22%3A%22chat%22%7D