manifests: Inherit from Project sagano

[This is just a demonstration/testing change; the git repository
 for Sagano is definitely going to change location at least]

Fedora CoreOS predates the time of bootable containers.  As such,
it's actually pretty large (relatively speaking).  Project Sagano
is a fresh take on more minimal base images.

At the same time, we want to de-duplicate efforts.  With this,
CoreOS cherry picks a few manifests from the Sagano "tier-0" and
"tier-1".

There's *definitely* more we can share between the two, but
this is a notable starting point.

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "sagano"]
+	path = sagano
+	url = https://gitlab.com/cgwalters-playground/sagano

manifests/bootable-rpm-ostree.yaml

@@ -0,0 +1 @@
+../sagano/tier-1/bootable-rpm-ostree.yaml

manifests/bootupd.yaml

@@ -0,0 +1 @@
+../sagano/tier-0/bootupd.yaml

manifests/fedora-coreos-base.yaml

@@ -3,6 +3,7 @@
 # core functionality.
 
 include:
+  - firmware.yaml
   - system-configuration.yaml
   - ignition-and-ostree.yaml
   - file-transfer.yaml

manifests/fedora-coreos.yaml

@@ -20,9 +20,6 @@ conditional-include:
   - if: basearch == "aarch64"
     # Fixup for kdump on aarch64 AWS instances
     include: kdump-aarch64-aws-workaround.yaml
-  - if: basearch != "s390x"
-    # And remove some cruft from grub2
-    include: grub2-removals.yaml
   - if: basearch == "ppc64le"
     # Need OSTree autopruning on ppc64le (because kernels aren't compressed)
     # until we increase the size of /boot.

manifests/firmware.yaml

@@ -0,0 +1 @@
+../sagano/tier-1/firmware.yaml

manifests/grub2-removals.yaml

@@ -0,0 +1 @@
+../sagano/tier-0/grub2-removals.yaml