overlay coreos-base/misc-files: add ami oem files

found by booting stable on AWS: `find /usr/share/oem` + checking the
content of files created by base Ignition.

Signed-off-by: Mathieu Tortuyaux <mtortuyaux@microsoft.com>

sdk_container/src/third_party/coreos-overlay/coreos-base/misc-files/files/oems/ami

@@ -0,0 +1,11 @@
+/etc/systemd/system/amazon-ssm-agent.service
+/etc/systemd/system/nvidia.service
+/etc/systemd/system/multi-user.target.wants/amazon-ssm-agent.service
+/etc/systemd/system/multi-user.target.wants/nvidia.service
+/etc/systemd/system/multi-user.target.requires/coreos-metadata-sshkeys@core.service
+/etc/eks
+/oem/ssm
+/oem/units
+/oem/base/
+/oem/bin/
+/oem/eks/