feat(apps): Make auth_token optional to promote public keys

[kofrezo]

Nudge users to use public keys instead of auth tokens by removing the default token generation

[brainexe]

the createapp command does not generate a token anymore, as createapp still assumes pre_save generates a token, which this MR removes:
reproduce:

createapp --non-interactive
# resulting app: auth_token=None app_id=None public_keys=0

Suggestion: either generate a token in createapp when none is given, or fail on an empty token. Either way, the Token (empty for auto generated one) prompt needs updating

[kofrezo]

the createapp command does not generate a token anymore, as createapp still assumes pre_save generates a token, which this MR removes: reproduce:

createapp --non-interactive
# resulting app: auth_token=None app_id=None public_keys=0

Suggestion: either generate a token in createapp when none is given, or fail on an empty token. Either way, the Token (empty for auto generated one) prompt needs updating

This is fine. This is only used on the development setup locally to setup a test user and app and this is setting the environment variables properly.