[Relax][Frontend][TFLite] Add tests coverage for SPACE_TO_BATCH_ND and BATCH_TO_SPACE_ND

[rknastenka]

Changes
Add tests in test_frontend_tflite.py.
Lower SPACE_TO_BATCH_ND / BATCH_TO_SPACE_ND through TOPI in tflite_frontend.py.
Use tf.raw_ops.BatchToSpaceND in the test because tf.batch_to_space_nd is not available in this TF build.

Why the TFLite frontend changed
The frontend was calling relax.op.nn.space_to_batch_nd / relax.op.nn.batch_to_space_nd, which aren’t implemented in this checkout. I updated the TFLite frontend to lower these ops via TOPI packed calls so conversion works and the new tests can pass.

Test:

pytest test_frontend_tflite.py -k "test_space_to_batch_nd or test_batch_to_space_nd"

related to #18971

[gemini-code-assist]

Code Review

This pull request updates the TFLite frontend to implement batch_to_space_nd and space_to_batch_nd using call_dps_packed with TOPI functions, and adds unit tests for these operations. Feedback includes a correction for an incorrect argument count in the batch_to_space_nd call and a recommendation to use to_int_list for shape and padding parameters to ensure type safety within the Relax IR.

[tlopex]

LGTM