implement intercept publish message event on ManagedMqttClient

[hannasm]

Discussion on this pull request can be found at @1470

[hannasm]

It seems these are the errors from the CI

CSC : error CS7027: Error signing output with public key from file 'D:\a\MQTTnet\MQTTnet\certificate.snk' -- Invalid public key. [D:\a\MQTTnet\MQTTnet\Source\MQTTnet\MQTTnet.csproj::TargetFramework=netstandard1.3]
CSC : error CS7027: Error signing output with public key from file 'D:\a\MQTTnet\MQTTnet\certificate.snk' -- Invalid public key. [D:\a\MQTTnet\MQTTnet\Source\MQTTnet\MQTTnet.csproj::TargetFramework=netstandard2.0]
CSC : error CS7027: Error signing output with public key from file 'D:\a\MQTTnet\MQTTnet\certificate.snk' -- Invalid public key. [D:\a\MQTTnet\MQTTnet\Source\MQTTnet\MQTTnet.csproj::TargetFramework=netstandard2.1]
CSC : error CS7027: Error signing output with public key from file 'D:\a\MQTTnet\MQTTnet\certificate.snk' -- Invalid public key. [D:\a\MQTTnet\MQTTnet\Source\MQTTnet\MQTTnet.csproj::TargetFramework=netcoreapp3.1]
CSC : error CS7027: Error signing output with public key from file 'D:\a\MQTTnet\MQTTnet\certificate.snk' -- Invalid public key. [D:\a\MQTTnet\MQTTnet\Source\MQTTnet\MQTTnet.csproj::TargetFramework=net5.0]
CSC : error CS7027: Error signing output with public key from file 'D:\a\MQTTnet\MQTTnet\certificate.snk' -- Invalid public key. [D:\a\MQTTnet\MQTTnet\Source\MQTTnet\MQTTnet.csproj::TargetFramework=net6.0]
CSC : error CS7027: Error signing output with public key from file 'D:\a\MQTTnet\MQTTnet\certificate.snk' -- Invalid public key. [D:\a\MQTTnet\MQTTnet\Source\MQTTnet\MQTTnet.csproj::TargetFramework=net7.0]
CSC : error CS7027: Error signing output with public key from file 'D:\a\MQTTnet\MQTTnet\certificate.snk' -- Invalid public key. [D:\a\MQTTnet\MQTTnet\Source\MQTTnet\MQTTnet.csproj::TargetFramework=net452]
CSC : error CS7027: Error signing output with public key from file 'D:\a\MQTTnet\MQTTnet\certificate.snk' -- Invalid public key. [D:\a\MQTTnet\MQTTnet\Source\MQTTnet\MQTTnet.csproj::TargetFramework=net461]
CSC : error CS7027: Error signing output with public key from file 'D:\a\MQTTnet\MQTTnet\certificate.snk' -- Invalid public key. [D:\a\MQTTnet\MQTTnet\Source\MQTTnet\MQTTnet.csproj::TargetFramework=net48]
CSC : error CS7027: Error signing output with public key from file 'D:\a\MQTTnet\MQTTnet\certificate.snk' -- Invalid public key. [D:\a\MQTTnet\MQTTnet\Source\MQTTnet\MQTTnet.csproj::TargetFramework=uap[10](https://github.com/dotnet/MQTTnet/actions/runs/7661927677/job/20882238981?pr=1915#step:8:11).0]