* Avoid copying buffer from ReadOnlySequence as  ReceivedMqttPacket body

* Use ReadOnlySequence.FirstSpan if possible.

* add ReaderExtensionsBenchmark

* update benchmark

* fix fixedHeader incorrect read
Co-authored-by: NChristian <6939810+chkr1011@users.noreply.github.com>

use Memory-Copy
Co-authored-by: NChristian <6939810+chkr1011@users.noreply.github.com>

Refactor code of MqttBufferWriter

* Avoid to call MqttPacketBuffer.Join() when SendPacketAsync

* Safely cleanup the PacketFormatterAdapter

* Keep buffer.Join when mqtt over webSocket

* null checking for IHttpContextFeature.HttpContext

Extend reset client statistic to reset all stats

dispose the AsyncSignalWaiter before setting it to null to prevent memory leak
Co-authored-by: NMario Zelger <mario.zelger@confer.ch>

1546 possible bug in server repeatedly sending the same message to client subscribed with cleansession=false (#1569)

Also cleanup `MqttClientSessionsManager._subscriberSessions` when session is taken over by a new one with CleanSession=true, fix #1552 (#1553)

1552 mqttnetservermqttclientsessionsmanager subscribersessions is not proper removed on special case (#1562)