Inelastic QENS Fitting interface refactor

[robertapplin]

Description

The Inelastic QENS Fitting interface is by far one of the better Indirect/Inelastic interfaces in terms of code quality and maintainability. Its structure largely uses the MVP pattern to compartmentalise the Qt Framework and separate it from the logic stored in the model. As a consequence, the QENS Fitting interface has a large number of automated tests, and is easier to extend and maintain.

However, there are still a number of issues that can make a big improvement to the quality of this code.

Plan

• Refactor FitTab class #36390
• Make IqtTemplateFunctionModel and ConvTemplateFunctionModel similar and share code #37190
• Use MultiFunctionTemplate classes for MSDFit and FQFit tabs #37191
• Review InelasticFitPropertyBrowser class #37291