MEDIUM: ssl: add FIPS elliptic curve check for AWS-LC

MEDIUM: ssl: add FIPS elliptic curve check for AWS-LC

Add ssl_fips_check_curves() which validates the configured curve list
against the FIPS-approved NIST P-curves (P-256, P-384, P-521).  Each
colon-separated name is resolved to a NID via OBJ_txt2nid() so all
standard aliases (P-256, prime256v1, secp256r1) are handled uniformly.
A NULL list is silently accepted since the global defaults were already
overwritten with FIPS values at init time.

The check is called right after SSL_CTX_set1_curves_list() in both the
bind (ssl_sock_prepare_ctx) and server (ssl_sock_prepare_srv_ssl_ctx)
configuration paths.