chore: Add Makefile target to deploy snapshot

[irvinlim]

Adds a Makefile target to deploy snapshot into K8s cluster using make deploy.

Additional changes:

1. Moved kustomize edit logic into helper generate-kustomization.sh script, and updated the logic to support generating a brand-new kustomization.yaml which avoids clobbering the main config/default configuration path.
2. Clean up some accidental changes.
3. Also push snapshot Docker image tag, which always points to the latest snapshot image tag.

[codecov]

Codecov Report

Merging #35 (7244f1e) into main (5f120c8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #35   +/-   ##
=======================================
  Coverage   49.74%   49.74%           
=======================================
  Files         159      159           
  Lines        7988     7988           
=======================================
  Hits         3974     3974           
  Misses       3831     3831           
  Partials      183      183           

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