Avoid mutating SSLContext in SSLServer.

[ioquatix]

I think that we shouldn't mutate the SSLContext in SSLServer and instead be more proactive about setting the right defaults.

               |   FrozenError: can't modify frozen OpenSSL::SSL::SSLContext: #<OpenSSL::SSL::SSLContext:0x0000000104d3f3b0 @verify_mode=0, @verify_hostname=true, @servername_cb=#<Proc:0x0000000104d3f1a8 /Users/samuel/Developer/socketry/async-http-native-io/external/falcon/lib/falcon/environment/proxy.rb:78>, @session_id_context=nil, @max_proto_version=771, @min_proto_version=771>
               |   → /Users/samuel/.gem/ruby/3.3.0/bundler/gems/openssl-d3d857cd1e4d/lib/openssl/ssl.rb:536 in `initialize'
               |     /Users/samuel/.gem/ruby/3.3.0/gems/io-endpoint-0.7.2/lib/io/endpoint/ssl_endpoint.rb:125 in `new'
               |     /Users/samuel/.gem/ruby/3.3.0/gems/io-endpoint-0.7.2/lib/io/endpoint/ssl_endpoint.rb:125 in `block in bind'
               |     /Users/samuel/.gem/ruby/3.3.0/gems/io-endpoint-0.7.2/lib/io/endpoint/ssl_endpoint.rb:124 in `map'
               |     /Users/samuel/.gem/ruby/3.3.0/gems/io-endpoint-0.7.2/lib/io/endpoint/ssl_endpoint.rb:124 in `bind'
               |     /Users/samuel/Developer/socketry/async-http-native-io/lib/async/http/endpoint.rb:185 in `bind'
               |     /Users/samuel/.gem/ruby/3.3.0/gems/io-endpoint-0.7.2/lib/io/endpoint/bound_endpoint.rb:13 in `bound'
               |     /Users/samuel/.gem/ruby/3.3.0/gems/io-endpoint-0.7.2/lib/io/endpoint/bound_endpoint.rb:83 in `bound'
               |     lib/falcon/service/server.rb:41 in `block in start'
               |     /Users/samuel/.gem/ruby/3.3.0/gems/async-2.10.2/lib/async/task.rb:163 in `block in run'
               |     /Users/samuel/.gem/ruby/3.3.0/gems/async-2.10.2/lib/async/task.rb:376 in `block in schedule'

[rhenium]

Can we just skip assigning the session ID context if SSLContext is already frozen, for now?

I agree SSLServer shouldn't mutate SSLContext, but I don't feel safe to change the behavior without deprecating it first, as that could break existing user programs in a tricky way.

[rhenium]

SSLContext#set_params is useful only for TLS clients so the session ID context should not be set here (which only makes sense for servers).