Change ListProviders to run as an activity.

Contrary to what I thought before, our documentation includes Android KeyStore
providers in our list of algorithm support, so run ListProviders as an
activity so that those providers are included.

Bug: 35793879
Test: Ran run_update_crypto_support.sh
Change-Id: I88332bfa1faa67d113e5fd4bc94d0c651a59c51d