Add platform contraints for GOAMD64 (#3251)

The new constraints `//go/constraints/amd64:v1` to `v4` can be used to
mark a platform as supporting the corresponding level of `GOAMD64`.

To use the new feature, users would supply their own platform:

```starlark
platform(
    name = "amd64_with_avx",
    contraint_values = [
        "@platforms//os:linux",
        "@platforms//cpu:x86_64",
        "@io_bazel_rules_go//go/constraints/amd64:v3",
    ],
)
```

and then specify the platform with `--platforms`.