Angstrom offsets

[j-c-c]

Adopt Relion >=3.1 convention of using angstrom valued offsets when storing/saving offsets in metadata.

This is a less invasive alternative to PR #1302. In this PR we allow for pixel_size agnostic ImageSources. This leaves current behavior of the code intact, but stores and saves offsets using _rlnOriginX(Y)Angst.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.60%. Comparing base (9210500) to head (b89914d).
⚠️ Report is 86 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1317   +/-   ##
========================================
  Coverage    90.60%   90.60%           
========================================
  Files          133      133           
  Lines        14348    14355    +7     
========================================
+ Hits         13000    13007    +7     
  Misses        1348     1348           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[j-c-c]

Closing this PR in favor of #1302