2855: Fix model save error

[krzywon]

Description

A flag was added to the TabbedModelEditor to differentiate documentation edits from model edits. This stops the editor attempting to generate the documentation when saving a model.

In the future, the two editor types should be different classes (#2863).

Fixes #2855

How Has This Been Tested?

Tested

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)

Licencing (untick if necessary)

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

[butlerpd]

works well on windows also. It basically was no allowing us to edit plugin models. However, it does now mean that once a plugin model has had its documentation generated, it is impossible to regenerate if I make corrections to my model.

I suggest that is a separate bug which also opens its own can of worms: what about built-in models? On the other hand it is suggesting yet again that we separate the "save" from the regeneration which would also be helpful when editing documentation.