This uses openmp threads to speed up the `Strings::join()` function which was causing CreateWorkspace to be excessively slow when writing to the algorithm history.
The speedup is not fantastic as it still takes about 8s to create a 1000x10000 workspace (using 8 threads), but it is an improvement on the 60s yielded by the original function.

A new version of the `join()` function was actually added to `Strings.h`, and is used when the iterators passed as arguments are not random access in nature. If this is the case, then the original function is used.

A test was added to `StringsTest.h` to make sure both `join()` functions are being tested.

Fix an apparent bug in FitPeaks.

New algorithm: ReflectometrySumInQ

Add MDFrameValidator to Mantid

Add plotting in log scale to directtools

Indirect - ISISEnergyTransfer - Custom Detector Grouping Option

ISIS SANS improve error messages

LoadMcStas property to only output summed eventworkspace

Autoprocessing on reflectometry GUI

Improvements to polarization analysis

Allow input workspaces to have bank ID 0 in fitting tabs of the Engineering GUI

Fix default Q binning in DirectILLReduction

Fix segfault when calibrating CORELLI with C60

Calibrate with bank numbers from SNAP instrument

New TOPAZ IDF for 2018B

Engineering GUI save Nexus file with all the other output after a focus

Add a MD workspace validator for checking that a MDWorkspace conforms to
a particular frame (e.g. HKL, QLab, QSample...)

Part of the code was checking if peaks were in range while another part
assumed that all were listed and would clear out the ones that aren't.
There was also (mostly) duplicated code which was removed.

Refs #22603.