Add support for per request MqttRpcTopicPair specification to ExecuteAsync method

[Temppus]

Describe the feature request

I am using MQTTnet.Extensions.Rpc to do RPC calls via MQTT (great library btw 👍 ).
I would like to use one IMqttRpcClient to do requests to different request/response topics. Prove me wrong but this is not currently supported by library, because ExecuteAsync method overloads only accepts methodName as parameter. So when I want to create dynamic MqttRpcTopicPair for each ExecuteAsync call I have to encode/serialize this to method name and parse it in custom implementation of IMqttRpcClientTopicGenerationStrategy.

Which project is your feature request related to?

• ManagedClient

Describe the solution you'd like

Add some kind of key value property maybe IDictionary<string, object> to TopicGenerationContext so I do not have to serialize/parse this "per request" topic generation from method name.

Describe alternatives you've considered

Add overload of ExecuteAsync with MqttRpcTopicPair as parameter ?

[Temppus]

I am open to create PR for this if feature will be accepted and design choice made.

[chkr1011]

Sounds like a good idea to me. To summarize it:

• Add a a new optional(!) parameter of type IDictionary<string, object> called "parameters" to the ExecuteAsnyc method
• Exposing the "Parameters" in the topic generation context so that the users can pass custom data which is required for topic generation.

[Temppus]

Created PR #1798

[Temppus]

Hey @chkr1011 can you find some time to review PR ?