Feature/remodel instance vs work search

[kwahlin]

• Control instance vs. work search term behavior via domain/range rather than via property chain axioms (makes much more sense in my opinion)
• Remove awkward ls:noneCategory and instead let ls:workCategory and ls:instanceCategory default to _categoryByCollection.@none. Whether instanceOf/hasInstance should be prepended in search can be inferred from their domains.
• Demonstrate behavior for ls:findCategory and ls:identifyCategory by setting :category :coercing (should be straight-forward to add corresponding sub-properties of ls:instanceCategory if/when needed)
• Move rdf:type to the top of sliceList so it will be overridden by workType/instanceType when those are applicable. (This doesn't work for mixed-type queries, e.g. type:Agent OR type:Instance, however mixed-type querying is already broken for other reasons so let's address that later.)
• Related changes in librisxl: Feature/instance vs work search librisxl#1736
• Related changes in lxlviewer: Handle changed instance/work search terms lxlviewer#1541
• New API tests include these terms: Add initial test suite for new Libris Search lxl_api_tests#44 (tests only basic querying so e.g. aggregating needs manual testing)