Scan from dict fix

[toastisme]

This fixes three bugs:

• Properties were not properly added to a properties dictionary in ScanFactory.from_dict before being passed to Scan.from_dict
• oscillation_width was not correctly converted to radians in Scan.to_dict when dealing with Scans with only one image
• Properties were being needlessly recreated when all properties already have the correct length. When a properties table is made from historical values that have different lengths (e.g. a single epoch but multiple exposure times), assumptions are made about epochs and exposure_time, which might give different values to historical data.

The first two are tested in test_scan_properties_from_dict. The third was picked up in test_experimentlist_dumper_dump_formats and test_experimentlist_dumper_dump_scan_varying.

[dagewa]

Thanks, can confirm this fixes the re-opened dials/dials#2606. I have not considered other aspects in this review

[codecov]

Codecov Report

Attention: 19 lines in your changes are missing coverage. Please review.

Comparison is base (39e463e) 42.40% compared to head (ceaae2f) 42.44%.
Report is 2 commits behind head on main.

Additional details and impacted files

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+ Coverage   42.40%   42.44%   +0.03%     
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  Lines       16358    16408      +50     
  Branches     3121     3141      +20     
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+ Hits         6937     6964      +27     
- Misses       8789     8805      +16     
- Partials      632      639       +7