dynamic inclusion of addons in ci

Why

As more addons get introduced, testing a "full" installation of bigbang on every MR is becoming troublesome, expensive, and tedious.

Solution

Use gitlab MR labels to determine which addons the MR must test. By leveraging CI_MERGE_REQUEST_LABELS, the MR owner can specify each addon by attaching labels to the MR.

Note that only addons should be allowed to toggle, and we should still core in every run.