This commit responds to the code review comments:

- Extract constant strings which are used multiple times into const string variables
- Throw immediately if multi period.
- Remove unclear call to getProperty("OutputWorkspace) in LoadMuonNexusV2
- Remove unnecessary includes and in doing so create forward declarations for TableWorkspace and Workspace2D
- Use std::move for string and workspace copying.
- Remove unnecessary pointer casting, which will be dealt with by the compiler.

This commit creates a RAII structure to encapsulate the omp_set_num_threads_call. This is necessary to restore the default number of threads once the algorithm has finished. This also adds a unit test to ensure the max threads is restored after the algorithm is executed.

After profiling the loader it was observed that CPU usage jumped to 100% in the LoadISISNexus loader. This is unnecessary usage given the small size of the Muon Nexus files. This lead to slow performance, where performance was between 10-100% slower than LoadMuonNexus1. With this change the speed difference is around 10% and with much less variability.

This commit adds a confidence measure to LoadMuonNexus3 algorithm so it can be loaded using the Load algorithm. It also adds a Muon file to the SystemTests data.

This commit adds time correction to the Muon loader. As the histogram data was loaded using the LoadISISNexus algorithm the time zero needed to be applied afterwards.

This commit updates the unit test for the Muon Nexus V2. This was required as the example file has changed since the test was written.

This commit introduces the strategy pattern to which enables the selection of the loading algorithm at run time. In this commit the following functionality is added:
- Structure for strategy pattern.
- Single period loading implementation, which features detector grouping and good frames data calculations.

This commit creates the following:
-LoadMuonNexus3 algorithm
-LoadMuonNexus3Helper file
-LoadMuonNexus3Test file
-Adds a MuonV2 file to the test data
This commit also implements the detector grouping calculation.

These standard algorithm functions are commonly understood so the comments do not really add anything helpful

Re #26897

Re #26897

Dynamically resize wb splash screen image based on screen resolution

Settings docs update

Fix Colorfills Scaling Differently if Done From Figure Options or the Context Menu

This should resolve some of the Huge splash screens we get with the workbench sometimes.

It also means we only have to maintain one splash screen image and not two resolutions of the same thing.

This commit converts the PSIBackgroundSubtraction algorithm to a data processing algorithm. This increases the clarity and transparency of the workspace history.

In order to do this, the operator overload which removed the background has been replaced with a CreateWorkspace call, which generates a workspace based on the backgrounds obtained, followed by a call to the child algorithm "Minus".