package/gstreamer1/gstreamer1: update tools comment

The tools option installs more than gst-launch and gst-inspect, so
simplify its prompt to just "install tools", and update the Config.in
help text. While at it, we list them alphabetically.

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>