Custom raw signers

[laurentsimon]

I use the term "raw signer" as per the description in #172. This was discussed in the SIG 12 June 24.

We'd like to have raw signer instantiations for:

• KMS signer
• HSM / PKCS11 signers

[mihaimaruseac]

#411 adds support for PKCS11. I need to review, but more eyes on it would also help.

[SequeI]

I assume KMS support is still something we want to add to complete the package of KMS/PKCS11 support? This issue is quite old, so just wanting to know it's still on the table as I wish to work on this. Would be a nice addition internally for RH.

cc @mihaimaruseac

[mihaimaruseac]

Yup, it would be nice to have it!