Restore DBAL array type compatibility

[ousamabenyounes]

Summary

Fix #3088

• restore the serialized array type removed by DBAL 4
• register it only when no existing array type is available
• preserve existing serialized role data without requiring a JSON migration

Test verification (RED → GREEN)

DBAL 4.4.4, unmodified master with only the new tests (RED):

Doctrine\DBAL\Types\Exception\UnknownColumnType: Unknown column type "array" requested.
ERRORS!
Tests: 6, Assertions: 12, Errors: 6.

Same tests with the fix (GREEN):

OK (6 tests, 26 assertions)

Production fix removed again (revert RED):

Doctrine\DBAL\Types\Exception\UnknownColumnType: Unknown column type "array" requested.
ERRORS!
Tests: 6, Assertions: 12, Errors: 6.

Full local suite

• PHP 8.2, 8.3, 8.4, and 8.5: OK (151 tests, 433 assertions) on each
• Symfony 7.4 on PHP 8.4: OK (151 tests, 433 assertions)
• composer validate --no-check-lock --strict: valid
• vendor/bin/php-cs-fixer check --verbose --diff: clean
• changed production lines: 100% covered (19/19)