Fix scalar arithemetic and add test cases (#6224)

Summary:
Add UnsquezeScalarPlaceholders pass to make scalars rank 1 Add MatchShapesPass to guarantee same rank for all inputs for ops that require it.
Additional fixes to make Scalar tests pass

Map which cases work and which don't.

Signed-off-by: Erik Lundell <erik.lundell@arm.com>
Change-Id: I4ea5e189e26cf7aff391ec153d525b2fb61aa16f

Fix shape issues

Change-Id: I0b8588cd5f8b284c25e806bb83bc788067d5b649

Pull Request resolved: https://github.com/pytorch/executorch/pull/6224

Reviewed By: mergennachin

Differential Revision: D64427014

Pulled By: digantdesai

fbshipit-source-id: 5295e9ffab1d848b111e0cb01aa0ce9142c20781