Add sum(idx is not None for idx in indices) == 1 check to fix incorrect mapping of multi-indexing in index function

[kamalrajkannan78]

This PR fixes tenstorrent/tt-forge-fe#817

Root cause

• This Multi indexing operation is root cause of this issue
• The current logic only supports single indexing for 3D and 4D tensors.
• Since there is no check to ensure exactly one valid (non-None) index (e.g., sum(idx is not None for idx in indices) == 1), multi-indexing scenarios are incorrectly mapped to _op.take which is not designed to handle multi-indexing, leading to shape mismatches in subsequent passes.

Fix

• A condition sum(idx is not None for idx in indices) has been added to ensure only single-indexing scenarios are mapped to _op.take.
• Multi-indexing cases are now correctly routed to adv_index, which is equipped to handle such scenarios.