Fix for image format dependencies during parsing

Fix for image format dependencies during parsing

local.conf is evaluated first before the distro configuration. This caused issues while parsing the
IMAGE_FSTYPES. The same set of IMAGE_FSTYPES did not throw the same switches deep in the other recipes.

We define
AGL_EXTRA_IMAGE_FSTYPES and AGL_EXTRA_INITRAMFS_FSTYPES for use in conf/local.conf or the device templates
which are added early on-top of the defaults:

AGL_DEFAULT_IMAGE_FSTYPES ?= "tar.xz ext4.xz"   (tar.xz for direct use, ext4.xz for direct use and CI)
AGL_DEFAULT_INITRAMFS_FSTYPES ?= "ext4.gz" (format for initramfs/initrd with smack labels)

Both sets can be overridden in the device configuration / template.

Device templates have been adapted accordingly.

Bug-AGL: SPEC-492

Change-Id: I962ee8cc461b307b494d13ce3a3ebca154bebc86
Signed-off-by: Jan-Simon Möller <jsmoeller@linuxfoundation.org>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/10047