Investigate syntax tree editing via node tracking

[matklad]

• https://github.com/dotnet/roslyn/blob/28191eef78568088a332a435dcd734fad1bd4fbf/src/Compilers/Core/Portable/Syntax/SyntaxNodeExtensions_Tracking.cs
• https://joshvarty.com/2015/09/18/learn-roslyn-now-part-13-keeping-track-of-syntax-nodes-with-syntax-annotations/
• SyntaxEditor could be more efficient when just operating on changes that do not involve lambda callbacks dotnet/roslyn#28378

I wonder if that's actually better than mutable-immutable syntax trees 🤔