10.x: translate value set Union, Add, Intersect and Except canonically (port of #478) #481

Problem

Union, Add, Intersect and Except run as SQL for every value set family but text on main since #478 (PR #480, merged as 46c31df). On release/10.x Intersect, Except and Add still run in memory only, and a Union is still array_cat, refused under equality, Count, GroupBy, Distinct, OrderBy, set operations, IN and ExecuteUpdate for every family.

Change

Cherry-pick e5be805, 571e82c, c2946fa and 18c264f with -x into a PR against release/10.x:

• ISetTypeDefinition.CanonicalizesInSql, the placeholders in ValueSetsMethodCallTranslator, and ValueSetSqlGuard.CanonicalExpander. The spike for Translate value set Intersect, Except, Add and a canonical Union for the non-text families with composed SQL #478 built the same code on EF Core 10 and 11, with identical SQL.
• CanonicalSetTranslationTests, NodaCanonicalSetTranslationTests, CanonicalSetOperationParityTests (an oracle, with the seed canonical-set-keeps-any-copy.patch), CanonicalSetCompositionTests, and the NULL-operand parity extended to the four operations.
• The docs, AGENTS.md, claims E17–E20, E35, E75 and E78–E82, and translation-support.json.
• The changelog rows go under [10.4.0] in the root, EF Core and EF Core NodaTime changelogs, not under main's [11.0.0-preview.1].

Done when

On release/10.x, the translation and parity tests pass on the EF Core 10.0.0 floor and on CI's newest-patch leg, on PostgreSQL 16 and 18. The seed fails the parity test. translation-support.json classifies the three operations as server except on text, and the translation-support probe passes.

Release

### Added in 10.4.0. Fixed only on release/10.x, so close it by hand.