Automatic merge from submit-queue (batch tested with PRs 40703, 40093, 40618, 40659, 39810)

Add AndSelectors helper function

I needed a simple way to logically `AND` two `Selectors` in https://github.com/openshift/origin/pull/11909 for [this](https://github.com/enj/origin/blob/7259bf75966b961cb9c7aa2c0ee2930471a59eed/pkg/oauth/registry/oauthclientauthorization/etcd/etcd.go#L95-L114).

This seems like the cleanest way to express that intent.
Signed-off-by: Monis Khan <mkhan@redhat.com>