Allow easy config of Monolog handlers

[timkelty]

Description

Adds a \craft\log\MonologTarget::$handlers to easily configure or override the handlers for Monolog.

Since this is a fairly common thing to want to (e.g. to send logs to a 3rd party service, I figured it should be a little more straightforward.

Before:

<?php

return [
    'components' => [
        'log' => function() {
            $dispatcher = new Dispatcher();
            foreach ($dispatcher->targets as $target) {
                $handler = new \Monolog\Handler\StreamHandler('php://stderr', \Monolog\Logger::ERROR);
                $target->getLogger()->setHandlers([$handler]);
            }
            return $dispatcher;
        },
    ],
];

After:

Adding a new target with only given handlers:

<?php

return [
    'components' => [
        'log' => [
            'targets' => [
                'handlers' => fn(\craft\log\MonologTarget $target) => [
                    (new \Monolog\Handler\StreamHandler(
                        'php://stderr',
                        \Monolog\Logger::ERROR,
                    ))->setFormatter($target->formatter),
                ],
             ],
        ],
    ],
];

Appending to default handlers:

<?php

return [
    'components' => [
        'log' => [
            'monologTargetConfig' => [
                'handlers' => fn(\craft\log\MonologTarget $target) => array_merge(
                    $target->getDefaultHandlers(),
                    [
                        (new \Monolog\Handler\StreamHandler(
                            'php://stderr',
                            \Monolog\Logger::ERROR,
                        ))->setFormatter($target->getFormatter()),
                    ]
                ),
            ],
        ],
    ],
];

[timkelty]

This should be gettable so you can set the configured formatter when setting your handler.

[timkelty]

If $this->handlers is an array, we take it as-is.

This makes the most intuitive sense to me, however, it isn't how \craft\log\Dispatcher::$targets works, where they are appended to the defaults. Happy to change it either way.

[timkelty]

getDefaultHandlers is not static because it needs access to $this->formatter and $this->name.

Its intended use is to be referenced in handlers when a Closure is used (when you want to append a handler to the defaults).