Missing `user` ID in CPAN accounts

[jackdeguest]

The following endpoints use user IDs such as FepgBJBZQ8u92eG_TcyIGQ (here OALDERS's ID), but not all CPAN accounts have IDs (mine does not), so they would only work with those who have a user ID, which is not likely intentional.

• /v1/author/by_user
• /v1/author/by_user/{user}
• /v1/favorite/{user}/{distribution}
• /v1/favorite/agg_by_distributions see sub options
• /v1/favorite/by_user/{user}