ci: migrate to Github Actions, close #546 (#750)

* ci: migrate to Github Actions

* ci: optimize on feedback

* ci: run gocov in correct dir

* ci: running after-build script always

* ci: giving test script execute permission

* ci: correct error handling on test script

* ci: more verbose test script

* ci: configure CC_TEST_REPORTER_ID env

* ci: check existence of CC_TEST_REPORT_ID variable, skip if unset

* ci: check existence of CC_TEST_REPORT_ID variable, skip if unset

* update changelog

* Update CHANGELOG.md

Co-authored-by: Joel Speed <Joel.speed@hotmail.co.uk>