include/json: Fix parsing of output from jq in json_array_tail()

include/json: Fix parsing of output from jq in json_array_tail()

The `json_array_tail()' function does not correctly handle return
values and parse output from jq, causing it to incorrectly handle
arrays that contain arrays or objects.

This commit modifies `json_array_tail()' so that it correctly
recognizes the type of data read from jq.