refactor: share common files between images; trim fedora-remote for a VM

- Move Kanidm/flatpak/finalize.d/sshd files to images/shared/{files,repos}
  and have build.sh overlay them for every image.
- fedora-remote: aggressive hardware trim (no firmware, no kernel-modules-extra,
  no non-QEMU guest agents), keep + enable qemu-guest-agent (Proxmox).
- Fixes the missing package-list (release step) for fedora-remote.

images/shared/files/kanidm-nsswitch.conf

@@ -0,0 +1,14 @@
+passwd:     kanidm compat systemd
+group:      kanidm compat systemd
+shadow:     files
+hosts:      files dns myhostname
+services:   files
+netgroup:   files
+automount:  files
+aliases:    files
+ethers:     files
+gshadow:    files
+networks:   files dns
+protocols:  files
+publickey:  files
+rpc:        files