Enhance debugging experience with new VSCode Debug Visualizer API

[NickAcPT]

Hey there,

With the release of VSCode 1.87, a Debug Visualizer API has been proposed.

Per the update log:

We have a new API that enables extensions to contribute visualizers for a variable. These visualizers might be either actions that run a command, such as opening a new editor, or trees embedded inline into the Debug views and that take the place of data's default representation.

Although I'm painfully aware that rust-analyzer "has nothing to do with debugging" (#15407), I firmly believe that we could harness rust-analyzer's knowledge of the codebase (memory layouts; etc) to provide a slightly better debugging experience.

Extra links:

• VSCode's own issue for debug visualization: Investigate debug visualization extension points microsoft/vscode#197287

[lnicola]

I firmly believe that we could harness rust-analyzer's knowledge of the codebase (memory layouts; etc) to provide a slightly better debugging experience.

Our knowledge of the memory layout is somewhat unreliable and pretty much stops there. Even if it was accurate, it wouldn't apply to optimized binaries. Only the compiler and a debugger have a chance to understand it, and you can count the production-ready debuggers on the fingers on one hand.

Sure, it would be nice to view an image::RgbImage in VS Code, but I don't see that happening.