Incorrect IPC schema encoding for multiple dictionaries

[XiangpengHao]

Describe the bug

The following test case should pass, but it errors:

thread 'tests::test_dict_schema' panicked at arrow-flight/src/lib.rs:851:56:
called `Result::unwrap()` on an `Err` value: ParseError("Unable to convert flight info to a message: Type `i64` at position 100 is unaligned.\n\twhile verifying table field `id` at position 100\n\twhile verifying table field `dictionary` at position 76\n\twhile verifying vector element 1 at position 56\n\twhile verifying table field `fields` at position 44\n\t while verifying union variant `MessageHeader::Schema` at position 24\n\twhile verifying table field `header` at position 24\n\n")

To Reproduce

    #[test]
    fn test_dict_schema() {
        let schema = Schema::new(vec![
            Field::new(
                "a",
                DataType::Dictionary(Box::new(DataType::UInt16), Box::new(DataType::Utf8)),
                false,
            ),
            Field::new(
                "b",
                DataType::Dictionary(Box::new(DataType::UInt16), Box::new(DataType::Utf8)),
                false,
            ),
        ]);

        let flight_info = FlightInfo::new().try_with_schema(&schema).unwrap();

        let new_schema = Schema::try_from(flight_info).unwrap();
        assert_eq!(schema, new_schema);
    }

Expected behavior

If the schema only has one dictionary, it would work just fine.

Additional context

[XiangpengHao]

Update: my latest finding is that it will panic whenever the dict_id is not 0

Probably related to: #5981

[XiangpengHao]

For anyone following along, I think the bug is from flatbuffer, and the workaround is to turnoff the verifier on receiving the data. The data seems to be correct, just the verifier is not happy with it:
XiangpengHao@be255bc

I don't have the bandwidth to fix it from flatbuffer, but if anyone wants to push this, I'm happy to share more my findings.