Use RunWidget in Indirect Diffraction

[robertapplin]

Description of work

This PR refactors the Indirect Diffraction interface so that it uses the new RunWidget. This is part of an effort to consolidate and reuse code in Indirect/Inelastic. See the attached issue for more details and future plans.

Part of #37381

To test:

Follow the test instructions here https://developer.mantidproject.org/Testing/Indirect/DiffractionTests.html

This does not require release notes because it is internal maintenance

Reviewer

Please comment on the points listed below (full description). Your comments will be used as part of the gatekeeper process, so please comment clearly on what you have checked during your review. If changes are made to the PR during the review process then your final comment will be the most important for gatekeepers. In this comment you should make it clear why any earlier review is still valid, or confirm that all requested changes have been addressed.

Code Review

• Is the code of an acceptable quality?
• Does the code conform to the coding standards?
• Are the unit tests small and test the class in isolation?
• If there is GUI work does it follow the GUI standards?
• If there are changes in the release notes then do they describe the changes appropriately?
• Do the release notes conform to the release notes guide?

Functional Tests

• Do changes function as described? Add comments below that describe the tests performed?
• Do the changes handle unexpected situations, e.g. bad input?
• Has the relevant (user and developer) documentation been added/updated?

Does everything look good? Mark the review as Approve. A member of @mantidproject/gatekeepers will take care of it.

Gatekeeper

If you need to request changes to a PR then please add a comment and set the review status to "Request changes". This will stop the PR from showing up in the list for other gatekeepers.

[robertapplin]

I don't know if this is some weird double rounding problem, but it might be worth looking at? I don't think it's part of this PR though.

Thanks for testing! This behaviour is expected because when the number of detectors is not divisible by the number of groups (i.e. there is a remainder), then an extra group is created to house the remaining detectors. So with the numbers that divide by 8 (the number of detectors in this case) to give a remainder (3, 5, 6, 7), there should be an extra group