task: #3588246 Extract DomainAccessManager static helpers to DomainAccessFields

Summary

Moves the 5 public statics on Drupal\domain_access\DomainAccessManager (getAccessValues, getAllValue, getDefaultValue, clearStaticCache, userCanAccessDomain) to a new Drupal\domain_access\Utility\DomainAccessFields class. The originals become @deprecated wrappers with @trigger_error() that delegate to the new class.

Issue: #3588246. Mirrors the precedent set by !358 for DomainStorage::createMachineName() -> Drupal\domain\Utility\MachineName::fromString().

Why

DomainAccessManager is a service whose 5 statics are de-facto public API in the ecosystem (domain_path, domain_shorturl, domain_extras/domain_access_linkit). Marking the class @internal in #3584261 surfaced the conflict — the service is internal, its statics are public. Splitting them clears the way for DomainAccessManager to become @internal in 4.0.0 with no remaining public surface.

The new statics are pure entity-field readers with no instance state or DI requirements. They naturally belong on a utility class, not a service.

Internal callers migrated

DomainAccessManager itself (its instance methods checkEntityAccess, hasDomainPermissions, getContentUrls now call the new utility), DomainAccessNodeHooks, DomainAccessEntityHooks (incl. the setDefaultValueCallback() in entityBundleFieldInfoAlter), DomainAccessDomainHooks, DomainAccessFormHooks, DomainAccessAdd, DomainAccessRemove, DomainContentHooks, DomainSourceSet, plus 7 functional test classes (DomainAccessAllAffiliatesTest, DomainAccessDefaultValueTest, DomainAccessElementTest, DomainAccessEntityReferenceTest, DomainAccessLanguageSaveTest, DomainAccessPermissionsTest, DomainAccessSaveTest).

Behavior changes

None. Strict superset:

• The new class implements identical behavior to the originals (function bodies copied verbatim except for trivial type tightening — see "Type tightening" below).
• Static cache stays in one place — moved into DomainAccessFields::$staticCache. The deprecated DomainAccessManager wrappers delegate, so external callers still hit the same (and only) cache. The old DomainAccessManager::$staticCache property is removed.
• getDefaultValue is set as a field default callback at runtime via setDefaultValueCallback() in hook_entity_bundle_field_info_alter, NOT stored in config — so changing the callback location does not require a config migration. The callback fires fresh on every entity_bundle_field_info_alter invocation.

Type tightening (in DomainAccessFields only — wrappers preserve original signatures)

• getAccessValues($entity, string $field_name = ...): array (was untyped $field_name, no return type)
• getAllValue($entity): bool (was no return type)
• getDefaultValue($entity, $definition): array (was no return type)
• clearStaticCache(string|int|null $entity_id, ?string $entity_type_id): void (was untyped)
• userCanAccessDomain($account, string|int $domain_id): UserDomainAccess (was untyped $domain_id; return type already present)

The deprecated wrappers on DomainAccessManager keep the original loose signatures, so the public BC surface is unchanged.

Out of scope (separate sweeps)

• Migrating the actual ecosystem callers: domain_path (3 files, 11 call sites), domain_shorturl (1 site), domain_extras/domain_access_linkit (1 site). They keep working through the deprecated path.
• Restoring @internal on DomainAccessManager — that goes in 4.0.0 once the wrappers are removed.

Test plan

• PHPCS clean on changed files.
• PHPStan level 2 clean on full module.
• CI lint stage (cspell/eslint/stylelint/phpstan/phpcs/composer) green.
• CI phpunit (D11 + previous-major D10) — pipeline running.