Fix #2444, Enforce keeping code coverage minimums up-to-date

[thnkslprpt]

Checklist

• I reviewed the Contributing Guide.
• I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution

• Fixes Enforce keeping coverage minimums up-to-date in Code Coverage CI workflow #2444
  • Adds an additional step in the code coverage workflow to check that the missed branches/lines variables are kept up to date. Note: This step will not run if the previous 'Confirm Minimum Coverage' step fails (it would be redundant anyway).

Testing performed
Tested all variations of coverage thresholds (above, below, split between lines/branches etc.) to confirm expected behavior.

New checks:

Confirm Minimum Coverage logic/failure is unchanged:

Expected behavior changes
Any PR that improves coverage will cause the workflow to fail now, unless the MISSED_LINES_ALLOWED and/or MISSED_BRANCHES_ALLOWED variables are updated (lowered) as well.

System(s) tested on
Debian GNU/Linux 11 (bullseye)
Current main branch of cFS bundle.

Contributor Info
Avi Weiss   @thnkslprpt

[thnkslprpt]

Note: Unlike the logic in OSAL (https://github.com/nasa/osal/blob/main/.github/workflows/standalone-build.yml), cFE doesn't currently check for full coverage of functions directly (only lines and branches). I can add that in here with this PR if desired.