Label language preferences + diff-pretty label-language prefs support

[jclerman]

This PR does not resolve a filed issue (I can file one if that's preferred).

I posted a question about this capability in the OBO Slack last week; this PR stems from the ensuing conversation.

• docs/ have been added/updated
• tests have been added/updated
• mvn verify says all tests pass
• mvn site says all JavaDocs correct
• CHANGELOG.md has been updated

Summary

Add initial support for specifying a language-preference when showing entity-labels. Use that support for the diff command's pretty format. Solution is designed to be extensible for use with the other diff formats, and for other ROBOT commands that show entity-labels.

Background

robot did not previously have support for preferring a particular language when showing entity labels. For ontologies with max-1 label per entity, that doesn't matter - but some ontologies designed to support multi-language use may have multiple labels (one per each of several languages). Although multiple labels per entity violates an OBO principle, it may be worth revisiting that decision. Meantime, non-OBO ontologies can also use this tool and would benefit from the extension immediately.

Details

Context/Plan: First of several PRs

With this PR, the first step in a 3 (or 4) step plan for adding language-preference support to ROBOT is delivered.

Steps:

1. This PR; ROBOT: diff (pretty): Add a reusable LanguagePreference helper and PreferredLanguageShortFormProvider, and wire a new --label-langs-priority option into diff so the pretty format can select entity labels by an ordered language list (with en→en-GB cascade, deterministic tie-breaking, a none token for untagged literals). NO CHANGE to behavior when the option is omitted.
2. In owl-diff: Provider injection: Add backward-compatible renderWriter overloads to MarkdownGroupedDiffRenderer and HTMLDiffRenderer that accept a caller-supplied ShortFormProvider for labels instead of building their own, so consumers can control label rendering (no ROBOT dependency added).
3. ROBOT: diff (markdown/html): Once the owl-diff change is released, pass ROBOT's PreferredLanguageShortFormProvider into the markdown and html renderers so --label-langs-priority works for all diff formats consistently.
4. ROBOT: Other commands: Reuse the same LanguagePreference/provider to add --label-langs-priority (or equivalent) to the other label-displaying commands — export, explain, and report.

Ordering: PR3 depends on PR2 being merged and released (new owl-diff version bump in ROBOT); PRs 1, 2, and 4 are independent.

Note about language-preference cascade

As part of this implementation, label-language preferences follow a "specificity cascade": More-general tags (e.g. "en") can match to more-specific ones (e.g. "en-GB"). However, label-values match to the most-specific-possible position in the preference-list, and are prioritized with that in mind. So:

• Binding (within a label): each label binds to the most specific preferred entry its tag matches (longest matching tag; exact beats cascade at equal length).
• Winner (across labels): the label bound to the earliest entry wins. Ties are broken by exact-over-cascade, then alphanumerically.
• Consequence: listing a specific tag after a general one (en,en-GB) deprioritizes it.

Future work

Remaining 3 steps (steps 2-4 as enumerated above). Note that the next step would be an update to owl-diff - not this repo.