Remove old Data analysis tab classes

[robertapplin]

Description of work

This PR removes the ConvFitTab, MSDFitTab, IqtFitTab and FqFitTab classes. Since the move to MVP a few years ago in the Data Analysis interface, all the functions for the tabs should be in the relevant Model-View-Presenter files for the relevant section of the GUI. This PR finally removes these classes so that new functionality is not added into them anymore.

Some of the changes might look a bit messy, but this is because this is only a stepping stone. There is still a lot of refactoring to do in this area, in particular surrounding the IndirectDataAnalysisTab class. I will continue with this refactor in a separate PR so that this one does not get too large. I have opened an issue to continue refactoring #36390

There is no associated issue.

To test:

1. Go to Interfaces
2. Then Inelastic Data Analysis
3. Select Add Workspace for each tab and enter the data below for the corresponding tabs
4. Select the corresponding fit functions
5. Click Run
6. Click Plot Spectra or Plot (depending on the tab). Try Plot Tiled on the Iqt tab (accessed via the down arrow on the Plot Spectra button)

Also try moving around the range selectors on the embeded plots (the dashed vertical lines).

Test Data

MSDFit Tab
Input file: osi92762_graphite002_elwin_eq.zip
Select Fit Type: MSDGauss

IqtFit Tab
Input file: irs26176_graphite002_iqt.zip
Tick Stretched Exponential
Select Flat background
Note: drag the EndX on the graph to the left a bit to miss the noise (0.15 I think)

ConvFit Tab
Input files: irs26176_graphite002_red.zip
irs26173_graphite002_res.zip
Select Fit Type: Two Lorenztian

F(Q) Tab
Input file: IN16B_125878_QLd_Result.zip
Select Fit Type: Chudley Elliott

This does not require release notes because it is an internal refactor

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[MohamedAlmaki]

Thanks for the refactoring, now the code is cleaner. Just a few comments

[MohamedAlmaki]

Tabs work as expected. Thanks for enhancing the code quality