[dev.typeparams] go/types: implement ch <- x where ch is of type parameter type
This is a port of CL 333712 to go/types, adjusted for the different
error reporting API and to position errors on the arrows.
Fixes #43671
Change-Id: I7d2de249e86d272c89a046f60e632e75848ff865
Reviewed-on: https://go-review.googlesource.com/c/go/+/335076
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>