make `hive app:create` / `hive app:publish` idempotent

Today you have to model your app deployment workflow around checking on whether an app already exists on Hive Console. It would be nicer to treat the app deployment creation/publish command as idempotent that allows successful runs to succeed if the manifest has not changed (in case you need to rollback or similar).

Start at the entry points for `hive app:create` and `hive app:publish`, then trace how each checks the existing app and manifest. Done means rerunning either command succeeds when the app already exists and its manifest is unchanged, supporting rollback or repeated deployment runs.

Written by the indexing model from the issue text.