CustomAuth refactor

[chaitanyapotti]

Motivation and Context

• remove hybrid aggregate login method
• refactor customauth params
  Jira Link:

Description

Removes hybrid aggregate login method
removes reddit login type since it's deprecated by reddit
update facebook to v20 api
refactor customauth createhandler api
simplify handlers

How has this been tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project. (run lint)
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[arch1995]

lgtm