twister: recording: Allow JSON data fields

Extend Twister Harness recording feature to allow selected data fields,
extracted from the log by a regular expression, to be parsed into JSON
objects and eventually reported in `twister.json` as `recording` list
property of the test suite.

With this extension, log records can convey layered data structures
passed from a test image as summary results, traces, statistics, etc.

This extension also allows flexible recording structure: a test image
can output different types of data records incapsulated into a fixed
set of fields, so `recording.csv` file columns are respected, whereas
some of the columns keep strings with json-encoded semi-structured data.

Signed-off-by: Dmitrii Golovanov <dmitrii.golovanov@intel.com>