Updated the `<TargetFrameworks>` property to include `net480`
to support .NET Framework 4.8. Added `<LangVersion>` set to
`latest` to use the latest C# language features. Enabled
nullable reference types by adding `<Nullable>` set to
`enable` for improved null safety.
Updated `DigitalData.MessagingService.Client.csproj`:
- Added NuGet metadata (PackageId, Authors, Company, etc.).
- Included `icon.png` as the package icon.
- Configured multi-targeting for `net462` and `net8.0`.
- Added XML documentation file generation.
Added `icon.png` binary file to the project.
Simplified `DigitalData.MessagingService.Client.csproj` by removing metadata properties and adding a `RabbitMQ.Client` package reference.
Added a new project `DigitalData.MessagingService.RabbitMQ` targeting `net462` and `net8.0` with a `RabbitMQ.Client` package reference.
Updated `DigitalData.MessagingService.sln` to reflect the new project structure, including new paths, GUIDs, and solution configuration mappings.
