* Set IsSessionPresent in CONNACK if client session exists

* Set IsSessionPresent in CONNACK if client session exists;
- restore white space differences to make comparison easier

* Add support for RetainHandling.

* Add support for No Local.

* Add support for _SubscriptionIdentifier_.

* Add more Unit Tests.

* Update docs.

* process all queued message befor server stops

* fix an issue

Co-authored-by: ablfzl <ablfzl21@outlook.com>

* Added option for how many subscriptions to send in a single call to the server.  aws iotcore limits this to 8

* Split subscription messages up to 8 at a time when reconnecting

Update README.md

fix typo

update function WithMessageExpiryInterval description

* Updated tests with public servers.

* Separated tests with TLS12 and TLS13.

Based on https://github.com/chkr1011/MQTTnet/issues/1138#issuecomment-846649937

Disallow to call MqttClient.ConnectAsync while Disconnect is pending.

Passes the Endpoint of the client before it disconnected

Fix UWP support broken in #1135

Add more checks for NET5_0

Fix #996
Fix #1010

Feature/pending appmsg acknowledge

Added workflow to  build debian/ubuntu packages

Deb packaging