Introduce FileStream

[f1ames]

Feature description

Introduce FileStream similar to FSStream proposal from v4.

FileStream items would point to filesystem items like files, directories, etc and should provides methods like stat, contents.

The concept is similar to Vinyl objects so the stream should allow filesystem items manipulations (similar to how it is done in Gulp, Grunt, etc).

Use case

Manipulating files in batches, listing filesystem, files pipelines.

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If you are interested in this issue or this stream type fits your use case, please upvote with :+1:.