Ironic is flexible for x86/x86_64 servers by supporting BIOS and UEFI.
But to deploy servers of other architectures, such as aarch64 or ppc64,
configuration(PXE boot file and config template) must be modified,
which means one Ironic conductor can only deploy baremetal machines of
one architecture.
This patch adds multi arch deployment support. For example, to deploy
x86_64 and aarch64 servers by one Ironic conductor.
Closes-Bug: #1582964
Change-Id: I628320aeb44b232a262d0843bc726a68d297e1f8