Refactor metadata extraction for `ScanImageImagingInterface`

[h-mayorquin]

I am trying to add the gin test for ScanImageImagingInterface #568

However, the metadata that we have right for ScanImageImagingInterface does not follow the the right format (the problem is that our format expected lists for imaging plane and two photon series and Ben added the metadata as dicts) and therefore the metadata validation fails.

The PR with the added test comes chained to this.

As a bonus, one of the warnings that was generated by improper use of dict_deep_update is removed

[CodyCBakerPhD]

retriggering tests

[CodyCBakerPhD]

LGTM - @h-mayorquin is this good to go?

[codecov[bot]]

Codecov Report

Merging #580 (9dc42a0) into main (856283e) will decrease coverage by 0.06%. The diff coverage is 90.32%.

@@            Coverage Diff             @@
##             main     #580      +/-   ##
==========================================
- Coverage   88.40%   88.34%   -0.07%     
==========================================
  Files          59       59              
  Lines        3201     3218      +17     
==========================================
+ Hits         2830     2843      +13     
- Misses        371      375       +4     

Flag	Coverage Δ
unittests	88.34% <90.32%> (-0.07%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...faces/ophys/scanimage/scanimageimaginginterface.py	88.37% <90.32%> (-0.09%)	:arrow_down:
src/nwb_conversion_tools/utils/dict.py	91.80% <0.00%> (-3.28%)	:arrow_down:

[h-mayorquin]

LGTM - @h-mayorquin is this good to go?

Yes.