* Introduced oej.io.Transport as the abstraction for the low-level transport of high-level protocols.
Now protocols such as HTTP/1.1 or HTTP/2 can be transported over TCP, QUIC, Unix-Domain, memory, and possibly over other low-level custom protocols too.
* Introduced oej.client.Request.transport(Transport) to specify Transport for each request.
* Introduced Transport to [HTTP2Client|HTTP3Client].connect(...) methods.
* Introduced [Client|Server]QuicConfiguration so that it can be used in other Connectors such as MemoryConnector.
* Introduced oej.server.MemoryConnector and EndPoint.Pipe for memory communication between peers, along with a MemoryTransport.
* Introduced QuicTransport as a wrapper for other Transports, so that QUIC can now also be transported over memory.
* Improved javadocs and documentation.
* Removed usage of ClientConnector.forUnixDomain() from FastCGIProxyServlet (ee10 and ee9).
* Replaced usage of HTTP3ServerConnector with QuicServerConnector in jetty-http3.xml.
* Fixed handling of Instruction notifications in case of re-entrance.
Now first clear the list, then notify to avoid that when re-entering the same instruction is notified multiple times.
* Introduced ContentSourceRequestContent, and updated ProxyHandler to use it.
Signed-off-by: Simone Bordet <simone.bordet@gmail.com>