- Lowered referenced Roslyn version to 4.8

- Support older .NET SDK / C# compiler versions

- Added `CSharpIndexer` and `CSharpMethod`

- Added `CSharpIdentifier.ToNonNullable()`

- Added `CSharpType.NullableContext`
- Added `CSharpProperty.IsRequired`
- Added `CSharpProperty.InitializerExpression`

- Renamed `CSharpConstructor` to `CSharpObjectCreation`

- Renamed `CSharpClass.BaseClass` to `.BaseConstructor`
- Preserve `TypeArguments` in `CSharpIdentifier.ToNullable()`
- Preserve `Nullable` in `CSharpIdentifier.ToInterface()`

- Added `CSharpEnumValue.Value`

- Updated `Microsoft.CodeAnalysis.CSharp` dependency

- Updated Microsoft.CodeAnalysis.CSharp to 5.0.0

Updated IDE settings

Updated CI checkout action

Updated Microsoft.CodeAnalysis.CSharp to 4.0.1