test: Add test for JSON library

This adds a test suite for the JSON library, testing both encoding and
decoding of all supported data types, including arrays, nested objects,
and basic types such as booleans, numbers, and strings.

Jira: ZEP-1607
Change-Id: I4f6ad7e2859a142e06d405e0760e91751e01a31f
Signed-off-by: Leandro Pereira <leandro.pereira@intel.com>