Show progress when waiting for file lock on package cache

Usually when I open a file in my editor, rust-analyzer quickly reports progress (scanning, downloading dependencies, etc).

However, if another process is holding a lock on the package cache, rust-analyzer provides not feedback, and it is unclear what is going on when looking at my editor. I tend to think "Is it done analyzing? Why am I not seeing feedback? Is something broken?".

It would be useful if the LSP would indicate that it is waiting for a lock on the package cache, in the same way it indicates when it is indexing, fetching dependencies, etc.

Start by tracing rust-analyzer's existing LSP progress reporting for indexing and dependency fetching, then locate the package-cache lock wait. Done means the editor receives a clear progress indication while that lock is held; the issue names no specific files or tests, so identify the relevant code and test entry points first.