Add CI Tests (Compare Outputs)

[ric-evans]

Let's add tests that will compare outputs to known outputs, for a mini-scale run.

Steps:

1. Run full-scale on HTCondor cluster (Full-Sized Scan Test Run on Condor #35) and compare/confirm results (a la Scan result to single numerical file #40) to known results from python/-version
   • UPDATE: this has turned out to be more complicated than it seemed, see Get Relative Tolerances for Pixel Datapoints from Production #60
2. Run mini-scale on CI (already implemented) and persist outputs
3. Add CI Test(s): Compare persisted mini-scale outputs against CI

When this is complete we can remove test-case-scan/, since all its code will be integrated into skymap_scanner/ and tests/.

[ric-evans]

Also, don't run the CI on "tags" (so we don't get near the org limit of 60 concurrent jobs):

on:
  push:
    branches:
      - '**'
    tags-ignore:
      - '**'

[ric-evans]

waiting on #40

Done

[ric-evans]

waiting for #46

Done