network: do not use ifcfg-rh NM plugin

Apparently eth0 in ProxyVM can be configured using plain keyfile plugin,
which is present on all distributions.
network: fix NM uplink config permissions

Otherwise NM will not use the file.
debian: Add new notification agent depends; remove other
debian: Added functionality to move desktop entry config files to /usr/share/qubes/xdg/autostart to preserve originals

Added trigger for new notify agent; removed trigger for old one