all: implement changes in Go 1.18

[gazerro]

These are commits in Go 1.18 that make changes that may need to be implemented in Scriggo:

• golang/go@1e57748 cmd/compile, go/types: allow any anywhere (as a type)

• golang/go@4dd5f09 constraints: new package

• https://go-review.googlesource.com/c/go/+/356512/ cmd/compile, types2: better error message for invalid type assertion

[gazerro]

Duplicate of #939.