trace: support time slicing options in `trace summary`

The summary will only include samples within the specified range.
Timed samples will be trimmed to the given time range.

Requested-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>