* add GitHub GraphQL api initial support
* support mutiple backends for e2e tests - initial commit
* add github backend e2e test (currently skipped), fix bugs per tests
* refactor e2e tests, add fork workflow tests, support fork workflow in GraphQL api
* remove log message that might contain authentication token
* return empty error when commit is not found when using GraphQL (align with base class)
* disable github backend tests
* fix bugs introduced after rebase of GraphQL and OpenAuthoring features
* test: update tests per openAuthoring changes, split tests into multiple files
* fix: pass in headers for pagination requests, avoid async iterator as it requires a polyfill on old browsers
* test(e2e): disable github backend tests
