Provide a path compatible with is_file

[VincentLanglet]

Feature Request

Q	A
New Feature	yes
BC Break	no

Scenario / Use-case

HI @frankdejonge
Related to dustin10/VichUploaderBundle#1217 (comment)

When using gaufrette, before downloading a file, the path is gauffrette://folder/file.jpg.
Running is_file on this path is returning true and then the file could be downloaded with this path too.

When using flysystem, $fs->readStream($path);, the path to use is basically the name of the file.
But this path is not compatible with the method is_file, which return false.

Is there a way to get a is_file compatible path without downloading the file and saving it somewhere ?

[VincentLanglet]

Closing in favor of dustin10/VichUploaderBundle#1217 (comment)