Allow multiple identities files

[remko-bw]

On one of my machines, I have 2 secret keys that I use for my passwords:

• One secure enclave key, protected by touch ID
• One standard age key, protected by a password

Some folders in my store have a recipients file with both identities in them, some only the password protected.

I'd like to be able for passage to use Touch ID when it can, and only prompt me for the password when it needs to use the password-protected key.

Passage only looks in one identities file, and as far as I know, I cannot combine password-protected age keys and non-password-protected keys (such as the secure enclave one) in one identities file, so I can't make passage behave this way. It does work with age directly when I pass both identities in the correct order.