cmd/compile: fix missing dict pass for type assertions

cmd/compile: fix missing dict pass for type assertions

For type assertions, if either src or dst type has shape, we must
convert them to dynamic type assertions.

Fixes #53309

Change-Id: Ia3362fa67c011febcbdb5b26f856d081b5c366de
Reviewed-on: https://go-review.googlesource.com/c/go/+/411617
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@golang.org>