`GenericDialect` should support multi-table DELETE and DELETE without FROM clause

According to the design policy, `GenericDialect` is intended to parse any SQL that other dialects can handle, but it currently fails to parse multi-table DELETE statements and DELETE statements without a FROM clause.

I think the expected behavior is that the following tests should also pass with `GenericDialect`.

https://github.com/apache/datafusion-sqlparser-rs/blob/2182f7ea71242a7e9674932d559baef67dae522d/tests/sqlparser_common.rs#L688-L735

从 tests/sqlparser_common.rs 的第 688-735 行开始，并使用 GenericDialect 运行其中引用的测试。跟踪多表 DELETE 语句以及不带 FROM 子句的 DELETE 语句的解析路径。使用 GenericDialect 使现有的两组测试都通过即表示完成。

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