[google|compute] Update Servers support

- Add missing "Server" properties
- Remove unnecessary property aliases
- When destroying a "Server" asyncronously return the "Operation" model instead of the raw operation response
- If zone is not set on "all" and "get" methods, use the list aggregated servers request (1 API call) instead of fetching all zones
- Add "list_aggregated_servers" request
- Fix "attach_disk" request
- Fix "detach_disk" request
- Add "get_server_serial_port_output" request
- Add "reset_server" request
- Add "set_server_disk_auto_delete" request
- Add "set_server_scheduling" request
- Add "add_server_access_config" request
- Add "delete_server_access_config" request
- Fix "set_tags" request
[google|compute] Improve Disks support

- Add missing "Disk" properties
- Remove unnecessary property aliases
- Use "Operation" instead of the "backoff_if_unfound" method when
  inserting a "Disk" or "Snapshot"
- When destroying a "Disk" asyncronous return the "Operation" model instead
  of the raw operation response
- Add "list_aggregatted_disks" request
- If zone is not set on "all" and "get" methods, use the list aggregated
  disks request (1 API call) instead of fetching all zones
- Fix a bug when inserting a snapshot (description was not merged at the
  body request)
- Fix tests
Merge pull request #2863 from frodenas/gce_servers

[google|compute] Update Servers support
Merge pull request #2854 from frodenas/gce_disks

[google|compute] Improve Disks support