fix(rome_fs): improve the messaging of the "unhandled file type" diagnostic

[leops]

Summary

Fixes #3329

This PR changes the rendering of the UnhandledDiagnostic diagnostic type, emitted by the OsFileSystem when an unknown file type is encountered. It adds an explicit error message and description, along with an information advices providing additional details. It also adds a specialized version of the error message when the unhandled file is a symbolic link, as that's the most common case for this error to be raised. Finally, it downgrades the severity of the diagnostic from error to warning, since this is not a "fatal" error that should cause the traversal to abort.

The diagnostic should now be printed as follow when encountering a symbolic link:

..\test-link\link internalError/fs ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Symbolic links are not supported

  i Rome does not currently support visiting the content of symbolic links since it could lead to an infinite traversal loop

In the less likely case that the CLI encounters a completely unknown file type, the following message is displayed instead:

..\test-link\unknown internalError/fs ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Encountered an unknown file type

  i Rome encountered a file system entry that's neither a file, directory or symbolic link

Test Plan

This diagnostic is emitted by low-level code in response to an event from the underlying file system, so it's unfortunately hard to reliably test and reproduce across platforms.

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[github-actions]

Playground for commit 4abac02

[ematipico]

Would it be possible to add some test that catches these cases? I am not sure if we can simulate a symbolic link, but we can definitely simulate the unknown file type

[leops]

Would it be possible to add some test that catches these cases? I am not sure if we can simulate a symbolic link, but we can definitely simulate the unknown file type

The issue is that this diagnostic is emitted by the OsFileSystem only, while the tests use the MemoryFileSystem that has no concept of symbolic links or unknown file in the first place, but I'll try come up with an implementation for that.