Need a clean API to distinguish directories from other files

[gramster]

As far as I can see, we have no good API that, given a path (as a Path or as a String), will tell whether the object being referred to is a directory or a regular file.

This seems related to issue #2883. I would argue that relying on something like File.exists is a poor substitute, as directories are files after all. Furthermore, we may want to identify other types of files (like device nodes, named pipes, etc).

[iposva-google]

Removed Area-Library label.
Added Area-IO, Triaged labels.

[sgjesse]

The class FileSystemEntity now provides a way of chacking the type of a path.

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Added Fixed label.

[kevmoo]

Removed Area-IO label.
Added Area-Library, Library-IO labels.