* Add support for LayerNorm fusion

- Implement FindFusedLayerNorm / AddFusedLayerNorm for expanded LN subgraphs,
  including residual AddN variants.
- Register fused op and extend tests
- ZENAI-3236,4365

Signed-off-by: Devasena Kirthika <Devasena.KirthikaS@amd.com>
Change-Id: I26cb8681337c9a6ce83ff2b1e952a537fbe940ba
Co-authored-by: nishant sarda <nishant.sarda@amd.com>