Implementation of Oauth of Github, Google and Microsoft

[feyruzb]

fixes #4160

The right way it should look after logging in

new added button to log in with github

Changes:

• added new buttons on login page for GitHub,Google Oauth authorization
• added functions createLink and getOAuthToken into authentication.thrift
• imported OAuth2Session in client.py
• added a case for Oauth authorization in login_user function
• added definition for thrift
• imported OAuth2Session in authentication.py
• added code to load the authentication configuration from
• added oauth method for authentication in performLogin function
• added oauth case in session manager
• added fields for server_config file in the server_config.json
• added oauth cases in auth.js
• added reusable providers dict to server config to allow easier adding of new oauth providers
• create a new function get_oauth_config for getting different providers configs in session manager
• added documentation for configuration

[vodorok]

Please see my remarks.

I have some additional comments apart from the direct in code messages:

• My major concern with the implementation is that the oauth related API and its implementation is not generalized enough. The configuration is good enough for the time being.
• I am not sure if we are allowed to use the Git Hub logo in our repo.
• Please invite @cservakt to review the JS and VueJS parts.

I did not do a thorough review of the oauth flow in authentication.py after you addressed the above issues I will do another round concentrating on that.

Thanks for the hard work!