Re #6191. Replace a usage of a SpectraDetectorMap method.

Perhaps the new code should be moved into a more cental place, but right
now I just want to get to the same behaviour without using the
SpectraDetectorMap class.
Re #6191. Move away from using the SpectraDetectorMap.

As noted in the old comment, this may impact performance. However, if the
SpectraDetectorMap is to be removed this is a necessary step and I will
look at improving performance if it turns out to be necessary.
Re #6191. Recover performance while not using SpectraDetectorMap

The previous change (ce9afb2) caused a x100 slowdown in the MaskDetectorsInShape
performance test. The changes here bring things back to where they were.
Re #6191. Fix my silly error.
Re #6191. Clear cppcheck warnings for this file.

Also a couple of other tidy-ups.
Re #6191. Tidy up includes.
Re #6191. Fix some errors in the test.

Seems like a holdover from older code - args that were really boolean were
being declared as ints and there was a problem if one path of an if-else
was taken (it isn't at present but will be shortly).
Re #6191. Add a method to resize the workspace to a specified size.

Also amend padSpectra() to resize to the number of detectors in the
instrument rather than using the SpectraDetectorMap. Of the 2 usages of
this method, one (SNSLiveEventDataListener) shouldn't care and the other
will be changed shortly so this is what we want.
Re #6191. Eradicate use of the SpectraDetectorMap in LoadEventNexus.
Re #6191. Remove unnecessary mentions of the spectra-detector map.
Re #6191. Remove use of SpectraDetectorMap from LoadSpice2D.
RE #6191. Test for detector ID.
Re #6191. Remove usage of SpectraDetectorMap.
Re #6191. Pass by reference, not value.
Re #6191. Add a method to set all the detector IDs at once.

Without having to call clear followed by add to make sure there was not
anything already there.
Re #6191. Don't use the SpectraDetectorMap.
Re #6191. Add a setDetectorIDs overload for lvalues.

In the one place that I've changed to use it I could infact have employed
std::move to bind to the other version but that would mean yet another
mac ifdef.
Re #6191. Remove SpectraDetectorMap use from LoadMuonNexus2.

It was just setting up a 1-1 mapping, which is what you get by default
anyway.
Re #6191. Remove use of SpectraDetectorMap.
Re #6191. Remove SpectraDetectorMap from comment.