dbus: add socket activation but do not enable it

The following changes are included:

1) install user unit files from upstream dbus
2) use absolute paths to config for --system and --session instances
3) make socket activation of user units configurable

There has been a number of PRs to address this, so this one does the
bare minimum, which is to make the functionality available and
configurable but defaults to off.

Related PRs:
 - #18382
 - #18222

(cherry picked from commit f7215c9b5b47dfb0a6dbe87ff33d7730729a32e5)
Signed-off-by: Domen Kožar <domen@dev.si>

pkgs/development/libraries/dbus/default.nix

@@ -44,7 +44,11 @@ self =  stdenv.mkDerivation {
       "--localstatedir=/var"
       "--sysconfdir=/etc"
       "--with-session-socket-dir=/tmp"
+      "--with-system-pid-file=/run/dbus/pid"
+      "--with-system-socket=/run/dbus/system_bus_socket"
       "--with-systemdsystemunitdir=$(out)/etc/systemd/system"
+      "--with-systemduserunitdir=$(out)/etc/systemd/user"
+      "--enable-user-session"
       # this package installs nothing into those dirs and they create a dependency
       "--datadir=/run/current-system/sw/share"
       "--libexecdir=$(out)/libexec" # we don't need dbus-daemon-launch-helper
@@ -81,4 +85,3 @@ self =  stdenv.mkDerivation {
     };
   };
 in self
-