Add reduction for osiris diffspec

[louisemccann]

Added a reduction step for OSIRIS diffspec when Run is clicked

To test:

Interfaces>Indirect>Diffraction
Set instrument to OSIRIS, mode to diffspec
Input: 89813
Calibration: osiris_041_RES10.cal
Inputs can be found in the unit tests \Build\ExternalData\Testing\Data\UnitTest

No need for vanadium

Fixes #19021 .

---

Reviewer

Please comment on the following (full description):

Code Review

• Is the code of an acceptable quality?
• Does the code conform to the coding standards? Is it well structured with small focussed classes/methods/functions?
• Are there unit/system tests in place? Are the unit tests small and test the a class in isolation?
• If there are changes in the release notes then do they describe the changes appropriately?

Functional Tests

• Do changes function as described? Add comments below that describe the tests performed?

• How do the changes handle unexpected situations, e.g. bad input?

• Has the relevant documentation been added/updated?

• Is user-facing documentation written in a user-friendly manner?

• Has developer documentation been updated if required?

• Does everything look good? Comment with the ship it emoji but don't merge. A member of @mantidproject/gatekeepers will take care of it.

[martyngigg]

Restores functionality that was accidentally removed in fixing a previous bug found in #18857.

I checked both modes on OSIRIS and each run the reduction and give the same result as 3.9.0.

[martyngigg]

@mantidproject/gatekeepers The doc test failure is unrelated and one of the current crop of unstable tests.

Can we get this merged ASAP, please?

[SimonHeybrock]

@martyngigg Ah, was this supposed to be merged into master?

[martyngigg]

@SimonHeybrock Yes that's okay. For the patch we generally cherry-pick the commits from master.