feat(pikvm): Move cert files from /tmp

We now have acme.sh copy cert files into a directory that's writable,
specifically into '/tmp', this happens outside the scope of this
script purely within acme.sh. Most mounts remain mounted read-only so
we amend this script to make the '/' mount point read-writable and move
cert files into their correct location before making the '/' mount
point read-only again.

pikvm_reload.sh

@@ -1,6 +1,8 @@
 #!/bin/bash
+rw
 cert_location='/etc/kvmd/nginx/ssl'
 for cert_file in 'server.crt' 'server.key'; do
+    mv --force --verbose '/tmp/'"${cert_file}" "${cert_location%/}"'/'
     chmod -v '0444' "${cert_location%/}"'/'"${cert_file}"
 done
 systemctl restart kvmd-nginx.service