Fully qualify references to generated interfaces

[simonmckenzie]

This is a copy of codecentric#89, reopening after the sunsetting of that project.

This addresses an issue where, when a class references a generated interface, those references are not fully qualified, resulting in an interface that doesn't compile. See codecentric#87.

The change is to precalculate the list of interface names that will be generated, and, during symbol string generation, replace unrecognised symbols with generated names where a single unambiguous match can be made between the symbol and the list of interfaces being generated.

For the example provided in codecentric#87, the code will now generate this output:

//--------------------------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by a tool.
//
//     Changes to this file may cause incorrect behavior and will be lost if the code is regenerated.
// </auto-generated>
//--------------------------------------------------------------------------------------------------

namespace Test
{
    [global::System.CodeDom.Compiler.GeneratedCode("AutomaticInterface", "")]
    public partial interface ITest1
    {
        /// <inheritdoc cref="Test.Test1.Get(ITest2)" />
        void Get(global::Test.Tests.ITest2 test);
        
    }
}


//--------------------------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by a tool.
//
//     Changes to this file may cause incorrect behavior and will be lost if the code is regenerated.
// </auto-generated>
//--------------------------------------------------------------------------------------------------

namespace Test.Tests
{
    [global::System.CodeDom.Compiler.GeneratedCode("AutomaticInterface", "")]
    public partial interface ITest2
    {
    }
}

[simonmckenzie]

Hi @ChristianSauer ,

I see the RoslynExtensions class is now marked with an explicit comment:

Source: https://github.com/dominikjeske/Samples/blob/main/SourceGenerators/HomeCenter.SourceGenerators/Extensions/RoslynExtensions.cs

Does this mean any customisations I want to apply should be moved into a different extensions class, to keep RoslynExtensions as a clean direct copy...?