Add OpenID Connect login support (#77)

* Add OpenID Connect login support
* Add docs for OIDC config with Google Auth
* Use Google styles for log in
- Add support for linking existing account
- Force users to sign-in with passoword first, when linking existing accounts
- Add support to create new user when using OIDC
- Add identities to user to prevent account take-ver
- Make tests mocking instead of being integration tests
- Manage session handling correctly
- use OmniAuth.config.mock_auth instead of passing auth data via request env
* Conditionally render Oauth button

- Set a config item `configuration.x.auth.oidc_enabled`
- Hide button if disabled

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Signed-off-by: Juan José Mata <juanjo.mata@gmail.com>
Signed-off-by: soky srm <sokysrm@gmail.com>
Co-authored-by: sokie <sokysrm@gmail.com>

test/application_system_test_case.rb

@@ -11,7 +11,7 @@ class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
 
     def sign_in(user)
       visit new_session_path
-      within "form" do
+      within %(form[action='#{sessions_path}']) do
         fill_in "Email", with: user.email
         fill_in "Password", with: user_password_test
         click_on "Log in"