go/types, types2: isParameterized must be able to handle tuples

go/types, types2: isParameterized must be able to handle tuples

CL 484615 rewrote isParameterized by handling tuple types only where
they occur (function signatures). However, isParameterized is also
called from Checker.callExpr, with a result parameter list which
is a tuple. This CL handles tuples again.

Fixes #59890.

Change-Id: I35159ff65f23322432557e6abcab939933933d40
Reviewed-on: https://go-review.googlesource.com/c/go/+/490695
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>