1681 misleading signature of mqttclientconnectasync mqttclientconnectresultcode expected but throws exception (#1749)

Update MqttClient.cs

Resolve breaking change where previously ConvertPayloadToString returned null if the payload was null

* replace lock/semaphore by readerwriterlockslim to avoid lock contention while dispatch messages

* Update MqttClientSubscriptionsManager.cs

removed comment out codes

* Update ReleaseNotes.md

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Co-authored-by: NZeheng Feng <hf944813@broadcom.com>
Co-authored-by: NChristian <6939810+chkr1011@users.noreply.github.com>

* Add new overload for options builder

* Refactor code

* Update ReleaseNotes.md

* Notify what subscription topics failed as part of the SynchronizingSubscriptionsFailedAsync callback

* Update ReleaseNotes.md

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

* ClientMessageQueueInterceptor continues with subscription processing.

* Update readme

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

* Add compatibility option for AWS

* Fix UWP build

* Fix comment in MqttClientOptions (#1706)

* Refactor naming

* Fix wrong option value

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Co-authored-by: NMichi <michael@volz.dev>

Add user properties to event args

Fix running state handling

* Moved the usage of certificate provider into the server listener so that each connection has the posibility of receiving a new SSL cert.

* Removed warning from unused field.

* Reduced changeds on original codebase.

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Co-authored-by: NJeff Scherrer <Jeff.Scherrer@vw.com>

Added compiler declaritive to check for WINDOWS_UWP on IsAssignableFrom call.

* Expose server session items

* Add support for custom session items for injected application messages

* Avoid some full memory barriers

* Reset in stats itself

* Updated MqttClientStatistics

* Fixed order of members as artifact from merge-conflict