go/types, types2: method recv type parameter count must match base type parameter count
Check receiver type parameter count when type checking the method
signature and report a suitable error (don't rely on delayed
instantiation and possibly constraint type inference).
While at it, simplify blank name recoding and type bound rewriting.
Stop-gap measure to avoid crashes in the compiler.
Fixes #51339.
For #51343.
Change-Id: Idbe2d32d69b66573ca973339f8924b349d2bc9cc
Reviewed-on: https://go-review.googlesource.com/c/go/+/387836
Trust: Robert Griesemer <gri@golang.org> Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Robert Findley <rfindley@google.com>