[Relax][Frontend][TFLite] Add BROADCAST_TO, EMBEDDING_LOOKUP, and SELECT_V2

[rknastenka]

This PR adds support for three new operators in the Relax TFLite frontend: BROADCAST_TO, EMBEDDING_LOOKUP, and SELECT_V2.

Passed all newly added unit tests using

pytest tests/python/relax/test_frontend_tflite.py -k "test_broadcast_to or test_embedding_lookup or test_select_v2"

reference #19412

[gemini-code-assist]

Code Review

This pull request updates the tvm-ffi subproject and expands the TFLite frontend for Relax by implementing support for BROADCAST_TO, EMBEDDING_LOOKUP, and SELECT_V2 operators, accompanied by new test cases. Additionally, convert_gather was updated to use astype instead of cast. Feedback focuses on ensuring the shape argument in convert_broadcast_to is correctly converted to a ShapeExpr or integer list to avoid inference errors, and recommending an explicit int32 cast for indices in convert_embedding_lookup to improve backend compatibility.

[tlopex]

LGTM

[tlopex]

Could you resolve the conflict so that we can merge it in?