Y24-524 - Refactor tube rack creation code

[KatyTaylor]

N.B. Putting this one on hold while we look into tube rack manifests, and confirm that they are a feature we want to retain. (Because if not, then there will be only one area of SS code that creates tube racks, so probably not the best time for refactoring)

Describe the Housekeeping
Refactor tube rack creation code that was written as part of sanger/limber#1696, with the aim having a central place in the code base for tube rack creation, that can be used by:

• the SpecificTubeRackCreation endpoint, created in the above story
• the tube rack manifest upload code
• future endpoints or ways of creating tube racks

See comments on PR https://github.com/sanger/sequencescape/pull/4416/files for refactoring suggestions.

See the tube rack manifest upload code app/sample_manifest_excel/sample_manifest_excel/upload/processor/tube_rack.rb for similar code to that in SpecificTubeRackCreation.

The other main area of tube rack creation code in SS is the Heron endpoint, which is being removed in this story - #4570 - but could be worth a look at the code in case it's useful here.

Additional context
At time of writing, the sanger/limber#1696 code is not yet merged into develop, but is in an epic branch.

It doesn't look like the tube rack manifests are currently being used - however, they are a generic feature and I think it's worth keeping them around for the time being, if we are aiming to have full support for tube racks. Could be worth a discussion with the users, though.