[AIRADSW-852] Fixing regression with slice-squeeze rewrite for scalar inputs

[urpetkov-amd]

Motivation

This PR #5004 caused a regression.

Fix a simplify_reshapes compilation failure for graphs containing a
slice -> squeeze -> pointwise sequence with a scalar companion input.

The find_slice_squeeze rewrite moves the squeeze after the pointwise
operation and restores the removed dimension on the operation's other inputs.
It previously handled every companion input with unsqueeze. For scalar
inputs, this did not produce dimensions compatible with the unsqueezed slice,
so pointwise shape validation failed with:

same_dims: mul: Dimensions do not match

This prevented affected ONNX models from compiling.

Technical Details

• Detect scalar companion inputs in the find_slice_squeeze rewrite.
• Restore scalar inputs with multibroadcast using the sliced input's output
  dimensions.
• Continue using unsqueeze for non-scalar companion inputs.
• Add the slice_squeeze_binary_scalar regression test to cover a
  slice -> squeeze -> mul(scalar) graph and verify its final canonical form.

This corrects the scalar edge case in the slice/squeeze matcher added by
PR #5004.

Testing

• Compiled cpe-v2-fp16-384x672.onnx successfully with
  migraphx-driver compile.
• Ran test_simplify_reshapes_test.exe: all 205 tests passed.

Changelog Category

Add a CHANGELOG.md entry for any option other than Not Applicable

• • Added: New functionality.
• • Changed: Changes to existing functionality.
• • Removed: Functionality or support that has been removed. (Compared to a previous release)
• • Optimized: Component performance that has been optimized or improved.
• • Resolved Issues: Known issues from a previous version that have been resolved.
• • Not Applicable: This PR is not to be included in the changelog.

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