AppCreateResponse: add split between app page URL and logs page URL

[thundergolfer]

Describe your changes

Last night when dog-fooding I hit a broken link:

Stopping app - keyboard interrupt received. Use `modal run --detach` to prevent KeyboardInterrupts from killing apps.
Timed out waiting for logs. View logs at https://modal.com/logs/ap-n6SUuGWdBCufjNisSwx2Ep for remaining output.

Sometimes the app overview page is best and sometimes we should take the client directly to the logs page (or tab, whichever). So I'm adding both URL options to the proto.

• MOD-3658

Backward/forward compatibility checks

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Check these boxes or delete any item (or this section) if not relevant for this PR.

• Client+Server: this change is compatible with old servers
  • yes, old servers will continue to send the app_logs_url on field 2, which is compatible data because this is just a rename.
• Client forward compatibility: this change ensures client can accept data intended for later versions of itself

Note on protobuf: protobuf message changes in one place may have impact to
multiple entities (client, server, worker, database). See points above.

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[mwaskom]

👍