Add flatbuffers to libcudf build

[galipremsagar]

Description

Without flatbuffers being added to the conda environment libcudf is being built in is causing the following build failures:

In file included from /nvme/0/pgali/cudf/cpp/src/io/parquet/arrow_schema_writer.cpp:26:
/nvme/0/pgali/cudf/cpp/src/io/parquet/ipc/Message_generated.h:6:10: fatal error: flatbuffers/flatbuffers.h: No such file or directory
    6 | #include <flatbuffers/flatbuffers.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[mhaseeb123]

We should specify the flatbuffers version to the same in https://github.com/rapidsai/cudf/blob/branch-24.10/cpp/cmake/thirdparty/get_flatbuffers.cmake#L33

[galipremsagar]

Should we specify the flatbuffers version to the same in https://github.com/rapidsai/cudf/blob/branch-24.10/cpp/cmake/thirdparty/get_flatbuffers.cmake#L33

Yes! Done 👍

[bdice]

I verified that this fix is necessary and should be included in 24.08. We were shipping flatbuffers headers in the libcudf package (see related issue #13230). That can clobber the actual flatbuffers package, if it installed in the user's conda env.