feat(mlx-distributed): add new MLX-distributed backend (#8801)

* feat(mlx-distributed): add new MLX-distributed backend

Add new MLX distributed backend with support for both TCP and RDMA for
model sharding.

This implementation ties in the discovery implementation already in
place, and re-uses the same P2P mechanism for the TCP MLX-distributed
inferencing.

The Auto-parallel implementation is inspired by Exo's
ones (who have been added to acknowledgement for the great work!)

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* expose a CLI to facilitate backend starting

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* feat: make manual rank0 configurable via model configs

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* Add missing features from mlx backend

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* Apply suggestion from @mudler

Signed-off-by: Ettore Di Giacinto <mudler@users.noreply.github.com>

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Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Signed-off-by: Ettore Di Giacinto <mudler@users.noreply.github.com>