3208: Fix copy/paste structure factor errors

[krzywon]

Description

This fix excludes the structure factor parameter from the items being updated during a copy/paste operation in the fitting widget. This was manifesting in multiple ways and this should fix them all. This also fixes an issue with copy/paste where checkboxes were added to parameters that previously did not have checkboxes.

Fixes #3208
Fixes #3558
Fixes #3939

How Has This Been Tested?

Tested locally.

Review Checklist:

Documentation (check at least one)

• There is nothing that needs documenting
• Documentation changes are in this PR
• There is an issue open for the documentation (link?)

Installers

• There is a chance this will affect the installers, if so
  • Windows installer (GH artifact) has been tested (installed and worked)
  • MacOSX installer (GH artifact) has been tested (installed and worked)
  • Wheels installer (GH artifact) has been tested (installed and worked)

Licensing (untick if necessary)

• The introduced changes comply with SasView license (BSD 3-Clause)

[rozyczko]

Before realizing that you've already fixed this, I attempted at addressing the issue.
Ended up with almost exactly your code.
LGTM.