Rewrite typecheck against x/tools/go/packages

This runs much faster than before.  This change removes all of the
async status output because all of the compute time is spent inside
go/packages, with no opportunity to update the status.

Adds testdata code to prove it fails when expected.

hack/verify-staticcheck.sh

@@ -68,7 +68,7 @@ while IFS='' read -r line; do
   all_packages+=("./$line")
 done < <( hack/make-rules/helpers/cache_go_dirs.sh "${KUBE_ROOT}/_tmp/all_go_dirs" |
             grep "^${FOCUS:-.}" |
-            grep -vE "(third_party|generated|clientset_generated|hack|/_)" |
+            grep -vE "(third_party|generated|clientset_generated|hack|testdata|/_)" |
             grep -vE "$ignore_pattern" )
 
 failing_packages=()

hack/verify-typecheck.sh

@@ -30,10 +30,9 @@ cd "${KUBE_ROOT}"
 
 make --no-print-directory -C "${KUBE_ROOT}" generated_files
 
-# As of June, 2020 the typecheck tool is written in terms of go/types, but that
-# library doesn't work well with modules.  Guidance is to rewrite tools against
-# golang.org/x/tools/go/packages.  Until that is done, force this tooling to
-# run in a fake GOPATH.
+# As of June, 2020 the typecheck tool is written in terms of go/packages, but
+# that library doesn't work well with multiple modules.  Until that is done,
+# force this tooling to run in a fake GOPATH.
 ret=0
 hack/run-in-gopath.sh \
     go run test/typecheck/main.go "$@" || ret=$?