utils/authority doesn't properly handle userinfo percent-encoding

[funkyshu]

Describe the bug
Certain characters like \ are disallowed in raw form in the userinfo section of a URI. They must be percent/url -encoded. However the vfs utility for handing authority does not handle decoding percent/url -encoded values.

To Reproduce
Steps to reproduce the behavior:

uri := `sftp://domain.com%5cuser@host.com:22/`
loc, err := vfssimple.NewLocation(uri)
if err != nil {
	panic(err)
}
fmt.Println(loc.URI())
fmt.Println(loc.(*sftp.Location).Authority.UserInfo().Username())

Expected behavior
loc.URI() should returns the still-encoded uri as expected but the fetch the username should return the decoded value: domain.com\user but it returns domain.com%5Cuser. This will pass the wrong username to the client which fails authentication.

Additional context
This will affect both FTP and SFTP.