Refactor CloneableGenerator

[sven-n]

When updating the nuget for Microsoft.CodeAnalysis.Analyzers, we're getting build errors for the CloneableGenerator:

Severity	Code	Description	Project	File	Line	Suppression State	Details
Error (active)	RS1035	The symbol 'GeneratorExecutionContext' is banned for use by analyzers: Non-incremental source generators should not be used, implement IIncrementalGenerator instead	MUnique.OpenMU.SourceGenerators	C:\Users\Sven\Documents\GitHub\OpenMU_2\src\SourceGenerators\CloneableGenerator.cs	37		
Error (active)	RS1035	The symbol 'GeneratorExecutionContext' is banned for use by analyzers: Non-incremental source generators should not be used, implement IIncrementalGenerator instead	MUnique.OpenMU.SourceGenerators	C:\Users\Sven\Documents\GitHub\OpenMU_2\src\SourceGenerators\CloneableGenerator.cs	35		
Error (active)	RS1035	The symbol 'GeneratorExecutionContext' is banned for use by analyzers: Non-incremental source generators should not be used, implement IIncrementalGenerator instead	MUnique.OpenMU.SourceGenerators	C:\Users\Sven\Documents\GitHub\OpenMU_2\src\SourceGenerators\CloneableGenerator.cs	48		
Error (active)	RS1035	The symbol 'GeneratorExecutionContext' is banned for use by analyzers: Non-incremental source generators should not be used, implement IIncrementalGenerator instead	MUnique.OpenMU.SourceGenerators	C:\Users\Sven\Documents\GitHub\OpenMU_2\src\SourceGenerators\CloneableGenerator.cs	77		

We'd have to update the generator to implement IIncrementalGenerator to be able to upgrade the nuget package. The new API seems to have some performance improvements, according to https://andrewlock.net/creating-a-source-generator-part-1-creating-an-incremental-source-generator/#background-source-generators