Support language matching in SOQL/Criteria API

[ledsoft]

As a developer, I want to be able to filter strings in SOQL/Criteria queries by their language. This is a feature not present in JPQL. However, SPARQL does support language matching (e.g., using the langMatches function) and it makes sense to allow this feature in JOPA as well.

Note that langMatches often works in conjunction with lang, which extracts language tag from a string literal. The language matching API in SOQL/Criteria API should take this into account. An example could then be something like:

SELECT t FROM Term t WHERE LANG(t.label) = :langParam