[Messenger][Process] add RunProcessMessage and RunProcessMessageHandler

[kbond]

Q	A
Branch?	6.3
Bug fix?	no
New feature?	yes
Deprecations?	no
Tickets	n/a
License	MIT
Doc PR	todo

When reviewing how I could replace my cron scheduler with symfony/scheduler, I realized I need a way to schedule processes.

Usage

use Symfony\Component\Process\Exception\RunProcessFailedException;
use Symfony\Component\Process\Messenger\RunProcessMessage;

try {
    $context = $bus->dispatch(new RunProcessMessage('something'));

    $context->exitCode; // int
    $context->output; // string
    $context->errorOutput; // string
catch(RunProcessFailedException $e) {
    $e->context->exitCode; // int
    $e->context->output; // string
    $e->context->errorOutput; // string
}

TODO:

• wire up
• tests

[kbond]

Looking for feedback before proceeding further.

[kbond]

Pending a resolution to #49813 (comment), I think this is ready.

[ro0NL]

generally what about just dumping payloads ($dump($messsage)) in CLI for -v[vv]?

[kbond]

Can you explain this a bit more, I'm not understanding what you mean.

[kbond]

I've renamed the classes per the review.

I've also added a RunProcessContext that's returned from the handler and a RunProcessFailedException that's thrown by the handler on failure. These will allow the message/exception to be serialized while still giving access to the result.

[kbond]

Comments addressed and PR description updated to show usage.

[fabpot]

Thank you @kbond.