model creation can't find plugin directory

[pkienzle]

Describe the bug

Error when trying to create a new plugin model from sasview.

To Reproduce

Steps to reproduce the behavior:

1. Go to 'Fitting > Add custom model'
2. Enter plugin name and click apply

Expected behavior

Write the new model file and test that the model produces a result. Should be using get_plugin_dir() to in TabbedModelEditor to find the output location.

Note that the code in sas.sascalc.fit.models.initialize_plugins_dir() should also be using get_plugin_dir() for the model location.

SasView version (please complete the following information):

• Version: 6.1.1.dev115+gcd63d947d.d20250913

Note: should make the version string on the About SasView box selectable for copy rather than having to start the python console to type: import sas; print(sas.__version__)

Operating system (please complete the following information):

• OS: N/A

Installation method (please complete the following information):

• Installed: git checkout

Additional context

Traceback

2025-09-29 17:50:16,319 : ERROR : sas.qtgui.Perspectives.Fitting.FittingWidget (FittingWidget.py:148) :: Traceback (most recent call last):
  File ".../src/sas/qtgui/Utilities/ModelEditors/TabbedEditor/TabbedModelEditor.py", line 272, in _onApply
    self.updateFromPlugin()
    ~~~~~~~~~~~~~~~~~~~~~^^
  File ".../src/sas/qtgui/Utilities/ModelEditors/TabbedEditor/TabbedModelEditor.py", line 353, in updateFromPlugin
    plugin_location = models.find_plugins_dir()
                      ^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: module 'sas.sascalc.fit.models' has no attribute 'find_plugins_dir'. Did you mean: 'get_plugin_dir'?

[pkienzle]

qtgui and sascalc should not have separate implementations of the plugin manager