BI-2539 - Add GitHub as Alternative OAuth Provider

[mlm483]

Description

Story: BI-2539.

bi-web PR: Breeding-Insight/bi-web#429.

Dependencies

bi-web: feature/BI-2539

Testing

Please include any details needed for reviewers to test this code

Checklist:

• I have performed a self-review of my own code
• I have tested my code and ensured it meets the acceptance criteria of the story
• I have tested that my code works with both the brapi-java-server and BreedBase
• I have create/modified unit tests to cover this change
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to documentation
• I have run TAF: <please include a link to TAF run>

[mlm483]

Closing, these changes are included in #473.