Add the option to ironic to place bootable ISO images into local
HTTP server's document root so that BMC could boot from there.
This is an alternative to Swift-based boot controllable via the
``[redfish]use_swift`` ironic configuration option.
Change-Id: I390fbb3a27f1b7d0170caff84f54d4ca40e6bcb2
Story: 2006569
Task: 36674