Make error messages for missing shared libraries more helpful

[zebreus]

The error messages for missing dynamic libraries do not provide any details about why a dynamic library could not be found. This PR makes them more helpful by including the searched paths and the reasons why the library was not found there.

The previous implementation would always show entry not found even when the actual filesystem error was something else.

Previous error message:

error: Spawn failed
╰─▶ 1: Linker error: File system error: entry not found

New error message:

error: Spawn failed
╰─▶ 1: Linker error: Failed to find shared library libexample.so: 
           /lib/libexample.so: entry not found
           /usr/lib/libexample.so: entry not found
           /usr/local/lib/libexample.so: entry not found

Description

[Copilot]

Pull Request Overview

This PR enhances error messages for missing shared libraries by including details on the searched paths and the underlying filesystem errors. Key changes include introducing a new LinkError variant (SharedLibraryMissing) with a corresponding FsErrors enum to capture single or multiple filesystem errors, and updating the module lookup logic in locate_module to wrap errors with these detailed messages.

Comments suppressed due to low confidence (2)

lib/wasix/src/state/linker.rs:533

• [nitpick] Consider adding a brief comment above the Display implementation for FsErrors to explain the formatting logic, which will aid future maintainers in understanding the custom error output.

write!(f, "\n    {}: {}", path.display(), error)?;

lib/wasix/src/state/linker.rs:3618

• [nitpick] Consider checking for duplicate paths when chaining library_path with DEFAULT_RUNTIME_PATH to avoid redundant filesystem lookups, especially if there may be overlap between the two sources.

let search_paths = library_path.iter()

[promptless]

📝 Documentation updates detected!

New suggestion: Add troubleshooting documentation for Wasmer runtime shared library errors