t/unit-tests: convert hash to use clar test framework

t/unit-tests: convert hash to use clar test framework

Adapt the hash test functions to clar framework by using clar
assertions where necessary. Following the consensus to convert
the unit-tests scripts found in the t/unit-tests folder to clar driven by
Patrick Steinhardt. Test functions are structured as a standalone to
test individual hash string and literal case.

Mentored-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Seyi Kuforiji <kuforiji98@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>