CRM/Upgrade - Snapshots should have name `snap_{OWNER}_{VERSION}_{NAME}`

CRM/Upgrade - Snapshots should have name `snap_{OWNER}_{VERSION}_{NAME}`

1. Prevents the trigger-based logging system from hitting the snapshots.
2. Makes the de-facto table names shorter (less likely to hit 64 char limit)
3. In practice, it should be easier to skim
4. Use the same pseudo-extension name that we use elsewhere (`civicrm`)