keycloak scope is case sensitive

Ideally, the scope used by BigBang should be all lower to match what we are used to see for 'scope' naming. Meanwhile, the keycloak.md should probably match the case of 'Gitlab' in each mentions. https://repo1.dso.mil/platform-one/big-bang/apps/developer-tools/gitlab/-/blob/main/docs/keycloak.md

My first attempt didn't work, was not sure what was wrong before I guessed that was a case issue.