This makes it so the clients don't have to wait for RS to become
responsive, potentially allowing them to do other things while RS
handles the connections.
Fixes#23306.
This commit converts TLS::TLSv12 to a Core::Stream object, and in the
process allows TLS to now wrap other Core::Stream::Socket objects.
As a large part of LibHTTP and LibGemini depend on LibTLS's interface,
this also converts those to support Core::Stream, which leads to a
simplification of LibHTTP (as there's no need to care about the
underlying socket type anymore).
Note that RequestServer now controls the TLS socket options, which is a
better place anyway, as RS is the first receiver of the user-requested
options (though this is currently not particularly useful).
This makes connections (particularly TLS-based ones) do the handshaking
stuff only once.
Currently the cache is configured to keep at most two connections evenly
balanced in queue size, and with a grace period of 10s after the last
queued job has finished (after which the connection will be dropped).
The current ProtocolServer was really only used for requests, and with
the recent introduction of the WebSocket service, long-lasting
connections with another server are not part of it. To better reflect
this, this commit renames it to RequestServer.
This commit also changes the existing 'protocol' portal to 'request',
the existing 'protocol' user and group to 'request', and most mentions
of the 'download' aspect of the request to 'request' when relevant, to
make everything consistent across the system.
Note that LibProtocol still exists as-is, but the more generic Client
class and the more specific Download class have both been renamed to a
more accurate RequestClient and Request to match the new names.
This commit only change names, not behaviors.
