Courtesy of Eva: Add µm support for .top, .stp files

[SylviaWhittle]

Adds a check during .stp and .top loading to see if the units are µm or nm and multiplies the real size by 1000 if so.

This is needed for @EvaMartinC to load some AFM images.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.27%. Comparing base (ac9753c) to head (5d897ee).
Report is 146 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #145      +/-   ##
==========================================
+ Coverage   74.62%   79.27%   +4.64%     
==========================================
  Files           8       11       +3     
  Lines         607      830     +223     
==========================================
+ Hits          453      658     +205     
- Misses        154      172      +18     

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[SylviaWhittle]

The lines added aren't tested but the code is direct from Eva. What do you think, @ns-rse? I could mock it potentially. But it would simply be a test testing if python successfully multiplies a value by 1000.

Alternatively I could ask for the files that need loading. Would the repo size increase be worth the lines being tested?

[ns-rse]

Simple and straight-forward (I had to think about the regex before understanding the grouping).

Perhaps merge and then address tests as a separate issue/pull-request using mocking as you say to set things up? 🤔

Aside : The test wouldn't really be whether Python *1000 rather it would show that our regex and the logic associated with the results are correct by doing the multiplication.

As a further aside have you seen how large the TopoStats repository and its associated history is when cloning? I might if I ever get time try and work out how to remove some of the larger files from the history.

[SylviaWhittle]

Eva has sent me example files that use um units, I'll add test cases for these 👍