[llvm] [llvm] Revise IDE folder structure (PR #89741)

[James Henderson via llvm-commits]

jh7370 wrote:

> > Backing up a moment - how many subfolders do you expect inside each top-level folder?
> 
> Exactly as shown. LLVM is the project with the most subfolders. There may be more in the future, depending on whether there are suitable categories.

Sorry, I should have been clearer that I meant in general, not specifically LLVM (i.e. including clang/lld/lldb/...), ideally broken down by subproject. It helps give a clearer indication as to the overall impact and the trade-offs between subfolders and screen real estate (which I acknowledge is a potential issue).

https://github.com/llvm/llvm-project/pull/89741