lib: os: Extend Json library API and type update

New Types:
* Added support for Generic Numeric type (float, 64-bit)
* Added support for Opaque string type.
* Added support parse Array data in object for seprate array parsing
New API for Json Array parsing Object 1 by 1:
* json_arr_separate_object_parse_init() init array parse
* json_arr_separate_parse_object() Parsing 1 Json Object
Rename token and lexer structures and publish those.

Signed-off-by: Juha Heiskanen <juha.heiskanen@nordicsemi.no>