BLD 1020: Easy access to Group Configurations page from Content Experiment component.

**Ticket: [BLD-1020] (https://openedx.atlassian.net/browse/BLD-1120)**

**Note: Functionality is complete, only BLD-1122 (Jasmine tests) if not finished.**

**Acceptance criteria:**

From the container page of a content experiment, there is already a line of text that says “This content experiment uses group configuration 'Name of the Group Configuration'”. We should make the ‘Name of the Group Configuration’ part a hyperlink to the Group Configuration page, with the selected group expanded. Page should scroll to the appropriate part of the page (e.g. if the group is the last one on the page, we should scroll to that last group automatically on hyperlink.)

**sandbox:** (http://studio.jmclaus.m.sandbox.edx.org/)

**@cahrens , @frrrances , @mhoeber , @explorerleslie** please review.
@polesye 
> lets do that on backend and pass into template group_configuration_link that will have 2 possible values: url (String) or None (when module is disabled).

Done, returns an url if split_test and user_partition otherwise None.
The check on ```settings.FEATURES.get('ENABLE_GROUP_CONFIGURATIONS')``` is left in template.