master-1aa18ef

metal : concurrently dispatch commands (#2358)

* metal: concurrently dispatch commands

Function `ggml_metal_graph_find_concurrency` will run and write
commands that can be issued concurrently to metal context `concur_list`
array, when `ggml_metal_graph_compute` is called for the first time.

* metal: don't call find_concurrency automatically.

* metal : code style changes

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Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>