Package cert-sh-functions: Information

- Use SHA256 for certificates (thx naf@) (closes #31538).

- Make DH bits and certificate days configurable.
- Always separate rm's options from arguments.

- Minor spec cleanup.
- ssl_generate(): Make errors fatal.
- Make new self-signed certificate if expired (closes: #19082).
- Make errors not fatal.
- Fix ssl_check_pem() (closes: #24983).
- Use 1024 bits for dhparam as default.
- Allow set number of bits as argument to ssl_make_key().
- Use 2048 bits for RSA key by default (closes: #31116).