Removes the file-part of the string, returning a reference to it.
impl<H> NoNullString<H>
where H: Allocator,
{
fn pop_file(&mut self) -> &mut NoNullStr
}Returns the now removed file-part.
This first searches for the last '/' in the string, removes the trailing part up to and including the '/' and returns a reference to the part after the '/'.