fix(core/services/fs): Returning empty dir while list a file path

[Xuanwo]

Which issue does this PR close?

None

Rationale for this change

As explained in code:

// If the path is not a directory, return an empty list
//
// The path could be a file or a symbolic link in this case.
// Returning a NotADirectory error to the user isn't helpful; instead,
// providing an empty directory is a more user-friendly. In fact, the dir
// `path/` does not exist.

What changes are included in this PR?

Returning empty dir instead of error while users trying to list over a file path.

Are there any user-facing changes?

Behavior changed when users list a file, they used to get an error.