Generalize secret spec

[laurivosandi]

This essentially should split in half

The artifacts that are generated as needed:

• Random strings
• Public private key pairs possibly in different formats (DER, PEM)
• Any derivatives of the above eg MD5, SHA256, PBKDF2, bcrypt

How to render them into secrets:

• As-is
• Hex encoded
• Base64
• Comma, space etc separated arrays
• Unrolling arrays into different keys

The second half could be adopted by Passmower to render OIDC client secret as it's gotten already quite large and applications are expecting items in different formats. Most notably Freescout requires claims to be part of the auth uri as GET parameters.