feat(mlx): add mlx backend

[mudler]

Description

This PR:

• Fixes Mlx backend #5164
• Fixes Backend: MLX #1638
• Fixes Using mlx for apple silicon #1468

Notes for Reviewers

Currently WIP

What works:

• MLX
• MLX-VLM blocked by Vanilla MacOS support Blaizzy/mlx-vlm#470

Signed commits

• Yes, I signed my commits.

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[github-actions]

yamllint Failed

Show Output

::group::backend/index.yaml
::warning file=backend/index.yaml,line=95,col=6::95:6 [comments] missing starting space in comment
::error file=backend/index.yaml,line=140,col=24::140:24 [trailing-spaces] trailing spaces
::warning file=backend/index.yaml,line=723,col=6::723:6 [comments] missing starting space in comment
::warning file=backend/index.yaml,line=928,col=3::928:3 [comments-indentation] comment not indented like content
::endgroup::

Workflow: Yamllint GitHub Actions, Action: __karancode_yamllint-github-action_2, Lint: backend

[mudler]

due to Blaizzy/mlx-vlm#470 mlx-vlm installed here is behind and does not support many new models, but this is a start!

[mudler]

arg, more failures as it's a really old version. we might need to drop the mlx-vlm from this PR for now