RFE: enhance error message "error in libcrypto" when key is too small

Description of problem:

After enabling FIPS on a system, the minimal length for RSA keys is 2048 bits.
If the user's RSA key length is 1024 bits, the following non-explicit/non-helpful message gets printed:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
debug1: Server accepts key: /root/.ssh/id_rsa RSA SHA256:mZrafjEjVNCD8qhXqmUf+D6JRUtW1JnkBVcXnDAwr30
debug3: sign_and_send_pubkey: RSA SHA256:mZrafjEjVNCD8qhXqmUf+D6JRUtW1JnkBVcXnDAwr30
debug3: sign_and_send_pubkey: signing using rsa-sha2-256 SHA256:mZrafjEjVNCD8qhXqmUf+D6JRUtW1JnkBVcXnDAwr30
debug1: identity_sign: sshkey_sign: error in libcrypto
sign_and_send_pubkey: signing failed for RSA "/root/.ssh/id_rsa": error in libcrypto
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

It would be great to print details on the error, instead of getting a generic error, which makes it hard to troubleshoot.

Version-Release number of selected component (if applicable):

openssh-clients

How reproducible:

Always

Steps to Reproduce:
1. Create a 1024 bits RSA key
2. Switch to FIPS
3. Try connecting

Actual results:

Generic error message

Expected results:

"Invalid key length" or similar message

Additional info:

To reproduce, make sure crypto-policies-20220223-1.git5203b41.el9_0.1.noarch is used, because this package doesn't enforce 2048 bits for RSA (newer packages do).