Set prec field based on min value during introspection

[shihab-dls]

Fixes #63

Following #62, we are now be able to set the prec field of attributes by parsing their min value.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.40%. Comparing base (840932c) to head (99fd3b2).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #64      +/-   ##
==========================================
+ Coverage   86.02%   86.40%   +0.37%     
==========================================
  Files           5        5              
  Lines         322      331       +9     
==========================================
+ Hits          277      286       +9     
  Misses         45       45              

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[DominicOram]

Looks good, thanks. Can we have some additional tests on if min comes back as not a float and maybe just parameterize a bunch of other potential values of min and what you would expect the prec to be

[DominicOram]

Looks good, thank you!

[DominicOram]

As found on the beamline you can get mins come in with 1e-7 notation . Can we have some tests on that?

[shihab-dls]

Converting min to decimal representation (which we did in i03) (i.e., something like f"{:.f}) is neater as it handles scientific notation, but it pads with zeroes (default is 6 decimal places), which thus requires an upper bound for precision like f"{:.16f}. This introduces floating point errors (e.g., f"{0.1:.16f} == 0.1000000000000001), which result in an erroneous precision. So, I've just added a more explicit helper function instead.

[DominicOram]

One minor comment in code, take it or leave it. Is there also a bug here where if the min comes back as positive e.g. 1e10 it will have a prec of 10? It's probably not a massive issue