Fix base path

[shurwit]

Description

Please provide a detailed description of the issue.
The base path used for this building block is /gr. Ideally, all of the BBs should use their service ID as the base path.

Acceptance Criteria

Please describe what it means for this issue to be considered complete.
Base path should be /groups. All relevant documentation should be updated to reflect this change.

Warning: In the Rokwire AWS environment, the load balancer routing will need to be updated with a rule for this new path.

We will still need to keep the old /gr base path with duplicated endpoints for backwards compatibility.