[TOSA] Conv3d legalization

- Extend Torch to TOSA conversion with full aten.conv3d coverage,
  mapping padding/stride/dilation configs and bias handling into canonical TOSA conv ops.
- Refactor TorchToTosa lowering utilities to share more code between conv variants.
- Update conversion tests plus PT1 xfail lists to reflect the newly supported 3D convolution paths.

Signed-off-by: Cathal Corbett <[email protected]>
Change-Id: Iaf1261e121dec1ddb84b814e9058bb7ebadd4de7

Author: catcor01

include/torch-mlir/Conversion/TorchToTosa/TosaLegalizeUtils.h

@@ -105,7 +105,7 @@ LogicalResult getConvOpsAccType(PatternRewriter &rewriter,
 FailureOr<Value> getConvBiasForNoneType(Operation *op,
                                         PatternRewriter &rewriter,
                                         Type inputElemTy, Type outputElemTy,
-                                        ArrayRef<int64_t> weightShape);
+                                        int64_t numOutputChannels);
 
 // Emit an explicit zero-valued `tosa.pad` around an NHWC tensor so that later
 // avg_pool lowering can run with `pad = 0`. `padExtents` is ordered as