Extend algorithm LoadInstrumentFromNexus

[Peter Peterson]

The current algorithm LoadInstrumentFromNexus has very limited functionality. It loads only muon Nexus files and gets only a small amount of information from it.

It can extended by taking code from algorithms that load instruments from nexus files (LoadEventNexus, CreateGroupingWorkspace, and CreateChunkingFromInstrument in #9511 are three). Each of them has very similar code that should be collected into a single workflow algorithm.

[Karl Palmen]

A look at the code shows:

CreateChinkingFromInstrument first attempts to get the instrument from the workspace. If there is no workspace, it runs loadIDFFromNexus and it also reads the instrument name from Nexus separately. If it does not run LoadInstrument in the event of loadIDFFromNexus not working.

CreateGroupingWorkspace first attempts to get the instrument from the workspace. If there is no workspace, it runs LoadInstrument with either the instrument name or IDF filename. It has no nexus file.

LoadEventNexus first attempts to LoadIDFFromNexus. If that does not work, it reads the Nexus file to get the instrument name then runs LoadInstrument with the instrument name.

[Karl Palmen]

LoadInstrumentFromNexus currently has no unit test. A unit test would be added in the course of work on this ticket.

[Stuart Campbell]

This ticket has been transferred to github issue ​10380