Add bootmode parameter to publishing metadata [RHELDST-18235]

From RHEL 8.9 and RHEL 9.3 onward UEFI boot will be available. The boot mode
must be specified for AMI images to make use of the change. This change adds
the bootmode into publish metadata to be used by cloudimg.

pubtools/_ami/tasks/push.py

@@ -109,6 +109,7 @@ def upload(self, push_item):
             "virt_type": push_item.virtualization,
             "root_device_name": push_item.root_device,
             "volume_type": push_item.volume,
+            "uefi_support": push_item.uefi_support,
             "billing_products": push_item.billing_codes.codes,
             "accounts": accounts,
             "snapshot_account_ids": snapshot_account_ids,