tests: lib: json: Added tests array decoding, encoding and int limits
tests: lib: json: Added tests array decoding, encoding and int limits

Added tests for:
- json_arr_parse
- json_arr_encode_buf
- integer limit testings

Signed-off-by: Ramiro Merello <44d6dec2a3225ed89c29d123afc99bb50b73da0e@itba.edu.ar>

finikorg/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr