Add phase table model

[jhaigh0]

Description of work

Part of the MVP workshop week.

Adds PhaseTableModel which holds an FDA context and some other state, previously in the presenter.
Some methods have been moved to the Model if they were only interacting with the context.
Tests updated, and a new test file created for tests only concerning methods now in the model.

Fixes #38104

To test:

Code review and https://developer.mantidproject.org/Testing/MuonAnalysis_test_guides/Muon_FDA.html#id5

This does not require release notes because refactoring change

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[rbauststfc]

Thanks for this, looks great and is functionally all working well when I ran the manual tests through.

I noticed one typo in the phasequad thread properties, and had a couple of other thoughts when looking through. Let me know what you think. If you feel like it might be worth trying any of them out then I'm very happy to pick up doing that, depending on what you prefer.

[jhaigh0]

Happy with the changes made in the latest commit that move the threading operations to the model 👍

[rbauststfc]

I've followed the manual testing steps since all changes have been made and everything's working well. All PR comments have been addressed, either by myself or Jonathan, and we've both approved each others changes, so this is ready to be gatekeepered.

[robertapplin]

Thanks for your hard work with this PR! The code separation between the Presenter and Model is much improved, and the Model also has its own test suite now.