Migrate GCP CA to 1.0

[lukehinds]

Google has now implemented 1.0 with various changes, this means we need to update the googleca code to 1.0

[bobcallaway]

@dlorenc do we need to move to a new KMS object in GCP (and do this before the signing session this Friday)?

[dlorenc]

We're still using the CA. We can create a new one whenever, but we'll need to be careful with the migration since the root is still pinned in cosign.

[lukehinds]

We also need to be mindful of the public instance (and their chosen implementation), although we don't know what that looks like just yet.

[nsmith5]

I think this is done now right? I think v1beta1 support just got deprecated as well

[dlorenc]

Yup!