Add group_ids field to replace groups

[rowanseymour]

If we're going to have to map uuids to ids for flows.. might as well do it for groups too and make that easier to index

[codecov-commenter]

Codecov Report

Merging #44 (426d91d) into main (fe5e3df) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #44   +/-   ##
=======================================
  Coverage   74.65%   74.65%           
=======================================
  Files           3        3           
  Lines         217      217           
=======================================
  Hits          162      162           
  Misses         33       33           
  Partials       22       22           

Impacted Files	Coverage Δ
indexers/contacts.go	77.52% <ø> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update fe5e3df...426d91d. Read the comment docs.