go/parser: check that go/defer expressions are not parenthesized

go/parser: check that go/defer expressions are not parenthesized

Logic matches the code in the syntax package.
This error was missing from go/parser and go/types.
Added some tests.

For #54511.

Change-Id: I418de4bd4c7169457b424366caae70227a92a761
Reviewed-on: https://go-review.googlesource.com/c/go/+/425795
Auto-Submit: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Robert Griesemer <gri@google.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>