Separate UnionAttribute into its own project

[hwoodiwiss]

fixes #147

• Splits the library into 2 projects, the attribute and the generator
• Moves common project items to the Directory.Build.props
• Updates Benchmarks to remove covering code that is no longer generated
• Updates tests to work with new project layout
• Adds SDK reference to PackAsAnalyzer
• Updates namespaces

Testing

To test this locally, use the following steps:

• Create a folder in the project root called .packages
• Create a file in the project root named NuGet.Config with the following contents:

<configuration>
  <packageSources>
    <add key="local" value="./.packages" />
  </packageSources>
</configuration>

• Open a command window in the project root and run dotnet build -c Release --no-restore
• Copy the output nupkg file from src\Dunet\bin\Release to the .packages folder
• Update integration tests to use Dunet 1.11.0, they should still pass, and control clicking on the attribute should (IDE dependent) take you to the decompiled attribute source.

[domn1995]

Am I correct in my understanding that consumers will continue to install just the Dunet package as they are today but will get the generator through Dunet.Generator transitively?

[domn1995]

Do we need this reference if Dunet.csproj references it?

[hwoodiwiss]

Yeah, for the test project we do, as Dunet.csproj doesn't forward the reference to Dunet.Generator.csproj, the same is true with the Benchmark project

[domn1995]

Just finished testing this out locally as per the PR instructions. Dude, this is awesome! Thanks so much for working on this! I've left a few comments, but overall, it's looking really good!

[hwoodiwiss]

Am I correct in my understanding that consumers will continue to install just the Dunet package as they are today but will get the generator through Dunet.Generator transitively?

Yeah, you'd still be able to just dotnet add package dunet, and both the analyzer and the attribute assembly will be included.

[hwoodiwiss]

Hmm, I'll take a look at this properly tonight (GMT)

[hwoodiwiss]

Ah, fixed it (I think).
It worked on my machine because I dev on Windows