Add new script `pack_as_twister.py` to convert memory footprint
data prepared by `./footprint/scripts/track.py` into JSON files
compatible with Twister report schema. Next, the data can be
transformed and uploaded to ElasticSearch data storage the same
way as memory footprint (and other) reports executed by Twister.
Add to `plan.txt` an optional column with the corresponding
test suite names for 'footprints' as an example for test instance
name composing with `--test-name` command argumnent.
Signed-off-by: Dmitrii Golovanov <dmitrii.golovanov@intel.com>