Add CoreML Quantize (#5228)

Summary:
## Motivation
Short term: TorchAO int4 quantization yields float zero point, but CoreML does not have good support for it yet. We will need CoreML int4 quantization for now.

Intermediate term: Before torch implements all CoreML-supported quantizations (e.g. palettization, sparcification, joint compression...), it will be great to have a way to use/experiment those CoreML quantizations.

## Solution
In CoreML preprocess, we add CoreML quantization config as a compile spec

Pull Request resolved: https://github.com/pytorch/executorch/pull/5228

Reviewed By: kirklandsign

Differential Revision: D62468184

Pulled By: cccclai

fbshipit-source-id: 9f4987d19a01eaf5e2814c9ff8089324174644f8