Plot transforms should be owned by Plotter objects not Data objects

[krzywon]

Describe the bug
The x and y transforms are currently owned by the Data objects that are held by in the Data Explorer. This is leading to issues when replotting data that was previously plotted and rescaled. Ideally, the transforms should be owned by each plot, not each data set. The only transform the data object should have is a suggested transform which is immutable.

This should be for 6.0.1, not 6.0.0, due to the number of places this would need to change.

To Reproduce
Follow the steps outlined in #1783

Expected behavior
Each new plot should have the default scaling.

SasView version (please complete the following information):

• Version: 5.0.0+