[cpp-tiny] adds support for form and query params, improves the code quality

Created by: AndersSpringborg

This is an improvement to cpp-tiny generator. It adds support for form and query params. Thenn it improves the code quality a tiny bit.

Can someone label this with client:cpp .... And hacktoberfest-accepted if this is valid.. :)

Technical commetee @ravinikam (2017/07) @stkrwork (2017/07) @etherealjoy (2018/02) @MartinDelille (2018/03) @muttleyxd (2019/08)