Auto calculate the amount of concurrent process for the broker

[mpoiriert]

The Draw\Component\Messenger\Broker\Comman\StartMessengerBrokerCommand require to pass the amount of concurrent process we want to start.

The amount of concurrent process is often base on the amount of CPU.

The calculation is done on a shell script before calling the broker.

This code is "copied" on all project using the broker.

We want to allow to specify the amount of process per core and the minimum so the StartMessengerBrokerCommand compute it.

Also the --concurent option should allow to receive 'auto' as the value to use the auto calculation of cpu.

Default value would be 1 process per core, and minimum process 1.

Note that the process per core need to be a float allowing to have less than a process per core (0.5).

para test is using this lib:

fidry/cpu-core-counter

Might be a good library to use.

Also we don't want to force the install of fidry/cpu-core-counter.

We could simply throw an exception stating it need to be installed if --concurent is set to auto and it's not present