Combine multiple DLLs into single final DLL

[zspitz]

Related: zspitz/ExpressionTreeVisualizer#80

This would be useful for #5, and also for #9 if we need to include our own copy of JSON.NET.

[zspitz]

This was mistakenly closed; the referenced commit is irrelevant.

[zspitz]

I haven't been able to confirm that SDK projects targeting .NET Framework don't support single-file publish, but simply adding <PublishSingleFile>true</PublishSingleFile> to the .csproj doesn't work -- referenced DLLs are included in the output folder as separate files.

(We're still on .NET Framework because VS -- and visualizers written for it -- is still on .NET Framework.)

[zspitz]

Current attempt is at https://github.com/zspitz/ANTLR4ParseTreeVisualizer/tree/single-file and failing. The visualizer DLLs compile, but only 2019 works; all the other combinations (2019.Standard, 2017, and 2017.Standard fail with:

Could not load file or assembly 'Microsoft.Xaml.Behaviors, Version=1.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.

[zspitz]

Some progress: After setting CreateTemporaryAssemblies="true", the DLLs seem to be loading properly on the debugger side, but failing on the debuggee side, for .NET Core. (.NET Framework works without a problem.)

Presumably, if we split the debugger and debuggee sides, that would resolve the issue.

Alternatively, we could simply ignore assembly-loading issues, including this one.