update oauth flow for Gitlab 15 compatibility

[gs-gunjan]

The PR contains two changes;

• OAuth implicit grant flow is being demised
• OAuth refresh token flow is being implemented

[github-actions[bot]]

Test Results

558 tests   557 :heavy_check_mark:  3m 15s :stopwatch: 107 suites      1 :zzz: 107 files        0 :x:

Results for commit 241366d5.

:recycle: This comment has been updated with latest results.

[kevin-m-knight-gs]

/easycla