Automatic merge from submit-queue (batch tested with PRs 46897, 46899, 46864, 46854, 46875)

Write audit policy file for GCE/GKE configuration

Setup the audit policy configuration for GCE & GKE. Here is the high level summary of the policy:

- Default logging everything at `Metadata`
- Known write APIs default to `RequestResponse`
- Known read-only APIs default to `Request`
- Except secrets & configmaps are logged at `Metadata`
- Don't log events
- Don't log `/version`, swagger or healthchecks

In addition to the above, I spent time analyzing the noisiest lines in the audit log from a cluster that soaked for 24 hours (and ran a batch of e2e tests). Of those top requests, those that were identified as low-risk (all read-only, except update kube-system endpoints by controllers) are dropped.

I suspect we'll want to tweak this a bit more once we've had a time to soak it on some real clusters.

For kubernetes/features#22

/cc @sttts @ericchiang