This patch adds NotificationServer, which runs as the "notify" user
and provides an IPC API for desktop notifications.
LibGUI gains the GUI::Notification class for showing notifications.
NotificationServer is spawned on demand and will unspawn after
dimissing all visible notifications. :^)
Finally, this also comes with a small /bin/notify utility.
This was actually rather painless and straightforward. WindowServer now
runs as the "window" user. Users in the "window" group can connect to
it via the socket in /tmp/portal/window as usual.
This is probably not the final design we'll want for this, but for now
let's run the HTTP client code as a separate user to reduce exposure
for the standard "anon" user account.
Note that "protocol" is also added to the "lookup" group, in order to
allow ProtocolServer to contact LookupServer for DNS requests.
LookupServer now runs as lookup:lookup, allowing connections from other
members of the "lookup" group.
This is enforced through file system permissions by having the service
socket (/tmp/portal/lookup) be mode 0660.
Now the LookupServer program can't overwrite other people's files if it
starts misbehaving. That's pretty cool :^)
This patch introduces the second MenuApplet: Audio. To make this work,
menu applet windows now also receive mouse events.
There's still some problem with mute/unmute via clicking not actually
working, but the call goes from the applet program over IPC to the
AudioServer, where something goes wrong with the state change message.
Need to look at that separately.
Anyways, it's pretty cool to have more applets running in their own
separate processes. :^)
For services explicitly configured as lazy, SystemServer will now listen
on the socket and only spawn the service once a client attempts to connect
to the socket.
When reaping a child, SystemServer will now match up child's pid with its own
record of the services, and respawn the service if keepalive is enabled for it.
For example, we want to restart the WindowServer if it crashes, but we wouldn't
want to restart the Terminal if it gets closed.
