Add path-filtering for PRs

[m-ringler]

CURRENTLY NOT WORKING

This seems to have the fundamental issue that individual jobs are required as status checks and not complete workflows.
See #37 which should have all checks passed, but is waiting for checks that were skipped.

Description

This PR makes Build and CodeQL job runs conditional in pull requests.
Czicompress-specific jobs are only run, when code that may affect czicompress is altered; and czishrink-specific jobs are only run for czishrink code changes.

Subproject changes are detected with a new reusable workflow in subproject-changes.yml.

Goals: Simplify PR validation, reduce energy consumption.

Fixes #29

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• PR.:
  • Test PR for #36 #37
• not PR:
  • czishrink: Manually triggered run of czishrink build on branch
  • czicompress: Manually triggered run of czicompress build on branch

Checklist:

• I followed the Contributing Guidelines.
• I did a self-review.
• I commented my code, particularly in hard-to-understand areas.

[codecov]

Codecov Report

Merging #36 (a498ca0) into main (fa6f38d) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #36   +/-   ##
=======================================
  Coverage   77.64%   77.64%           
=======================================
  Files          58       58           
  Lines        1897     1897           
  Branches      121      121           
=======================================
  Hits         1473     1473           
  Misses        401      401           
  Partials       23       23           

Components	Coverage Δ
czicompress	66.75% <ø> (ø)
czishrink	80.39% <ø> (ø)

[DaveyJonesBitPail]

This looks good! I would perhaps add an additional distinction between czishrink and the installer within its subfolder. I'll take a try at adding this after I finish remaining installer changes unless you get to it first.

[ptahmose]

LGTM - but I have to confess, it complicates matters (CI/CD-matters) considerably. I mean - I am sure it solves an issue, but at the price of increased complexity. This is not always a good deal I reckon.

[m-ringler]

Abandoning this PR. It's not working.