UEFI HTTP PXE Loaders flags
UEFI clients are capable of booting from HTTP or HTTPS if they are given a valid URL via DHCP filename option.
Let's create such PXE Loader options. The only difference from existing options is that it must contain hostname of the boot server. By default this will be TFTP Smart Proxy if set, Foreman unattended_url otherwise.
For better flexibility, two new provisioning settings will be introduced: port number and root path. This allows users easily run their own web server exposing TFTP directory with grub2 configuration files over HTTP on arbitrary root path.