storage/fs: change order of precedence for URL expansion - #322

testdir
|-- abc*
|   |-- file1.txt
|   `-- file2.txt
`-- abcd
    |-- file1.txt
    `-- file2.txt

❯ s5cmd cp 'testdir/abc*' s3://bigtmp/prefix/
cp testdir/abc*/file2.txt s3://bigtmp/prefix/abc*/file2.txt
cp testdir/abc*/file1.txt s3://bigtmp/prefix/abc*/file1.txt

1) if given source URL is a directory, it only walks the directory.
2) if given source URL has glob, it expands glob.
3) if given source is not glob or directory, it sends stat call to single file.