(1) Convert methods which don't use self to static
(2) Update documentation
(3) Fix workspace deletion not updating plot
(4) Fix behaviour of FDA interface such that the plot is updated after a fft calculation and the labels correctly represent the fft component being plotted.

This Commit gives users the option of setting the Lorth filter on polaris PDF. Previously this was hard coded to true but will now be turned off by default.

This was not correct, as if a parameter has changed the fit information (of function name ect) should remain.

Also this commit fixes some failing unit tests in fitting and the Muon context

Moves the appropriate unit tests from plotting_widget to the newly refactored plot_widget

Various plot fitting improvements:

(a) Multiple fits no longer plotted
(b) Fits stay in results table

Implement a UI file for the main view
Add interface definition for the view
Create structure for the widget

This commit does the following things:

(1) Sets the parent of the Muon Analysis GUI to be the main workbench window. This prevents the external plot sending the interface to the back.

(2) Moves the number_of_axes variable to the view.

(3) Adds in an external plotting button within the Plotting Widget View.

(4) Creates an external plotting model view class. This class delegates to either workbench, or mantidplot based plotting.

(5) Adds unit tests for the new feature

Fix error introduced in rebase

This commit does the following things:

(1) Sets the parent of the Muon Analysis GUI to be the main workbench window. This prevents the external plot sending the interface to the back.

(2) Moves the number_of_axes variable to the view.

(3) Adds in an external plotting button within the Plotting Widget View.

(4) Creates an external plotting model view class. This class delegates to either workbench, or mantidplot based plotting.

(5) Adds unit tests for the new feature

This commit adds the option for the full crystallographic density to powder SampleDensity

re: #28418

To facilitate future changes a custom table widget was implemented in the sequential fitting tab. This should enable log data to be easily added to the table.
Fix flake8 errorrr

This change makes it so tiled plots and data loading signals update the plots  in a smart way (e.g does not replot all the data if we are on the fitting tab)

Reintroduced a fit selected button
Sequential fit will fit all workspaces, and then select the last one to display.
Added custom parameter item, to  prevent string inputs, which cause errors for mantid.