[io-layer] When deleting a file, check for EROFS and verify if the file exists. Fixes...

[io-layer] When deleting a file, check for EROFS and verify if the file exists. Fixes #57629.

Linux has this particular behavior of returning ENOFS when unlinking from an read only FS.
Even if the file doesn't exists! Darwin does the sane thing and return ENOENT in this case.

To workaround this, if unlink returns EROFS, we stat the file and deal with that.