Bug 5133: OpenSSL 3.0 support (#694)

Bug 5133: OpenSSL 3.0 support  (#694)

This TLS update includes:

* Fix build with OpenSSL v3.
* Refactor RSA key generation to avoid deprecated RSA_*() APIs.
* Refactor DH parameter and key config to avoid deprecated DH_*() APIs.
* Refactor ECDH key creation to avoid deprecated EC_*() APIs.
* Deprecate ssl_engine support in builds with OpenSSL v1-.
* Disable ssl_engine support in builds OpenSSL v3+.

We deprecated/removed ssl_engine support (as summarized in the last two
bullets above) without providing an OpenSSL Providers-based alternative
because of the following factors:

1. We do not have the resources to update ssl_engine code to build
   (without deprecation warnings) with OpenSSL v3 when the feature is
   unused.

2. We do not have the resources to create an OpenSSL v3 Provider-based
   replacement for ssl_engine code that uses deprecated Engine APIs.

3. OpenSSL v3 deprecated Engine support (triggering deprecation warnings
   in applications that use Engine APIs with OpenSSL v3). Since Squid
   default builds use -Werror, doing nothing would break such builds.

4. Squid ssl_engine does not appear to be a popular feature.