server: add connection span for each connection

[niklasad1]

This PR adds another span to make it easier to see which connection that calls, errors and similar occur on.
The downside is that the logs because a bit hard to read with the standard tracing subscriber.

Example WS

2022-11-02T14:47:15.885354Z TRACE connection{remote_addr=127.0.0.1:56206 conn_id=0}: jsonrpsee_server::server: Request { method: GET, uri: /, version: HTTP/1.1, headers: {"host": "127.0.0.1:36521", "upgrade": "websocket", "connection": "Upgrade", "sec-websocket-key": "zOys8P04xwmfdDykx/yJXA==", "sec-websocket-version": "13"}, body: Body(Empty) }
2022-11-02T14:47:15.885645Z  INFO connection{remote_addr=127.0.0.1:56206 conn_id=0}: jsonrpsee_server::server: Accepting new connection 1/100
2022-11-02T14:47:15.886040Z DEBUG jsonrpsee_server::transport::ws: Send ping
2022-11-02T14:47:15.886520Z DEBUG connection{remote_addr=127.0.0.1:56206 conn_id=0}: jsonrpsee_server::transport::ws: Received pong
2022-11-02T14:47:15.886773Z TRACE connection{remote_addr=127.0.0.1:56206 conn_id=0}:method_call{method="say_hello"}: jsonrpsee_core::tracing: recv="{\"jsonrpc\":\"2.0\",\"id\":0,\"method\":\"say_hello\",\"params\":null}"
2022-11-02T14:47:15.886831Z TRACE connection{remote_addr=127.0.0.1:56206 conn_id=0}:method_call{method="say_hello"}: jsonrpsee_core::tracing: send="{\"jsonrpc\":\"2.0\",\"result\":\"lo\",\"id\":0}"
2022-11-02T14:47:15.886875Z TRACE connection{remote_addr=127.0.0.1:56206 conn_id=0}: jsonrpsee_core::tracing: send="{\"jsonrpc\":\"2.0\",\"result\":\"lo\",\"id\":0}"

Example HTTP

2022-11-02T14:53:21.910294Z TRACE connection{remote_addr=127.0.0.1:47568 conn_id=0}: jsonrpsee_server::server: Request { method: POST, uri: /, version: HTTP/1.1, headers: {"content-type": "application/json", "accept": "application/json", "host": "127.0.0.1:44977", "content-length": "62"}, body: Body(Streaming) }
2022-11-02T14:53:21.910566Z TRACE connection{remote_addr=127.0.0.1:47568 conn_id=0}:method_call{method="say_hello"}: jsonrpsee_core::tracing: recv="{\"jsonrpc\":\"2.0\",\"id\":0,\"method\":\"say_hello\",\"params\":[1,2,3]}"
2022-11-02T14:53:21.910627Z TRACE connection{remote_addr=127.0.0.1:47568 conn_id=0}:method_call{method="say_hello"}: jsonrpsee_core::tracing: send="{\"jsonrpc\":\"2.0\",\"result\":\"lo\",\"id\":0}"

Close #878

[jsdw]

Cool!

[lexnv]

LGTM! Thanks for taking care of this!