Allow custom `SocketOption`s to be set and get

We allow users to set `SocketOption`s on the client/server builder and to query `SocketOption`s on `ConnectionContext` API. Currently, these methods support only `SocketOption` constants from `java.net.StandardSocketOptions` and `io.servicetalk.transport.api.ServiceTalkSocketOptions`. However, the `java.net.SocketOption` API is generic and we should allow users to provide a custom implementation of this interface. We can match it with the `ChannelOption` that netty uses internally.

Trace the client/server builder APIs and the ConnectionContext socket-option methods, then compare their handling of StandardSocketOptions and ServiceTalkSocketOptions with Netty's ChannelOption mapping. Done means a custom java.net.SocketOption implementation can be accepted for setting and querying wherever these APIs support socket options.

Written by the indexing model from the issue text.