Limit the number of AES-GCM keys allowed in TLS. A new error is raised if this

limit is ever reached.

This is a FIPS 140-2 requirement from IG A.5 "Key/IV Pair Uniqueness
Requirements from SP 800-38D".

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7129)