hook+trace: adds hookid and type

The hookid is a unic identifier for a hook event.
Its purpose is to distinguish events that could match
different filters: a same event has a same id.

Also integrate the field "type" (of the event) in the
trace event.

Change-Id: I90b0b2d3a0846b673b993110d2752cc54db75bd8
Signed-off-by: José Bollo <jose.bollo@iot.bzh>