Properly set widget value when making a new item

[mwcraig]

This fixes #317 by setting the ipyautoui widget to the appropriate value when making a new item.

@JuanCab @Tanner728 -- I'm going to merge this in the morning if tests pass so that I can finally get this custom widget wrapped up, but if you want to try this out here are the steps:

1. Make a camera. (or observatory or..._
2. Save it.
3. Once the dropdown updates, select "Make a new..."
4. Select the item you made in step 1.

Prior to this fix you got a bunch of blank fields in step 4. Now it works.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.87%. Comparing base (d901d65) to head (b388fcc).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #318   +/-   ##
=======================================
  Coverage   73.86%   73.87%           
=======================================
  Files          27       27           
  Lines        3409     3410    +1     
=======================================
+ Hits         2518     2519    +1     
  Misses        891      891           

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[Tanner728]

Did a quick test of this and it works as expected.