- Add Concat (#21423)
- Add DepthToSpace (#21426)
- Add LeakyRelu (#21453)
- Add test scripts (#21427)
- Add ability to set coreml flags from python (#21434)

Also updated partitioning utils to support dropping constant initializers from a ComputeCapability's inputs. We copy these to a CoreML model so don't need the originals. If they remain as inputs ORT can't free them as they appear to be in use.

Misc changes
- Fix SkipLayerNormFusion incorrectly setting `modified`
  - causes unnecessary loops of the L2 transformers

Drop SkipLayerNormFusion change - need to investigate test failures.
Update session state and allocation planner to handle ORT format models where an EP drops constant initializers.

Refine the handling of initailizers that become unused in an ORT format model

…regatedPR

…regatedPR