Draft: Bring controller, routes, and settings form in to module

This PR attempts to bring the auth controller, routes, and settings form in the Social Auth module so those things do not need to be implemented in all the networks. This takes away a lot of the boilerplate code needed in the network modules but I'm concerned it will make it harder to customize behaviors when required.

Still to do:

• Clean up Network annotation strings
• Fix image paths in login block
• Remove \Drupal\social_auth\Controller\SocialAuthController since it only deals with buttons? The path resolution stuff will need to be refactored to \Drupal\social_auth\Plugin\Block\SocialAuthLoginBlock (to satisfy above task)
• Determine if \Drupal\social_auth\Settings and Network handlers stuff is really needed. Refactor and remove if not.
• Evaluate other network implementations to determine if this is really feasible