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.

[codecov[bot]]

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

```diff @@ Coverage Diff @@ ## main #693 +/- ## ========================================== + Coverage 42.40% 42.44% +0.03% ========================================== Files 186 186 Lines 16358 16408 +50 Branches 3121 3141 +20 ========================================== + Hits 6937 6964 +27 - Misses 8789 8805 +16 - Partials 632 639 +7 ```