feat: ForUpdateClause API + multi-table OF clause + ORDER BY after FOR UPDATE

[Copilot]

JSqlParser failed to parse FOR UPDATE OF t1, t2, t3 (only single table was supported) and FOR UPDATE OF t ORDER BY col (non-standard but valid Oracle ordering). Both caused ParseException at the grammar level.

Changes

New ForUpdateClause class

Container for the full FOR UPDATE state — mode, table list, wait options — surfaced via getForUpdate() on PlainSelect:

PlainSelect ps = (PlainSelect) CCJSqlParserUtil.parse(
    "SELECT * FROM t FOR UPDATE OF a, b.c, d SKIP LOCKED");

ForUpdateClause clause = ps.getForUpdate();
clause.isForUpdate();      // true
clause.getTables();        // [a, b.c, d]
clause.isSkipLocked();     // true

Grammar fix: multi-table OF clause

FOR UPDATE OF t1, t2, t3 now parses correctly. Select.forUpdateTable: Table replaced with forUpdateTables: List<Table>; getForUpdateTable() is retained as a backward-compatible alias returning the first element.

Grammar fix: ORDER BY after FOR UPDATE

Added optional ORDER BY production inside the FOR UPDATE grammar block. A forUpdateBeforeOrderBy flag preserves the original clause ordering in toString() / deparser output so round-trip fidelity is maintained.

Updated deparsers & validators

SelectDeParser and SelectValidator updated to iterate the full table list.

Oracle test coverage

for_update07.sql (multi-table OF) and for_update08.sql (ORDER BY after FOR UPDATE) are now in SpecialOracleTest.EXPECTED_SUCCESSES.