[ONNX] Constant folding to not add folded constant as initializer (#79552)
Previous behavior adds all folded values as initializers(model parameters).
Now only add folded values as initializers, if the original values were initializers.
Fixes: #78505
Pull Request resolved: https://github.com/pytorch/pytorch/pull/79552
Approved by: https://github.com/justinchuby, https://github.com/garymm
