Allow easier Monolog config

[timkelty]

Description

The most common scenario is to want to add a Monolog handler for a third party service. This is an attempt to make that a bit easier.

As it is, MonologTarget is very much geared toward Craft's use of it and is a bit difficult to extend. One could always just add a target using samdark\log\PsrTarget, (which MonologTarget extends), but you miss out on the default formatting and processors that Craft applies.

This PR allows MonologTarget to be constructed with a Closure for the logger property, allowing you to override anything.

Example: Add a custom log target with your own Monolog handlers and Craft's default formatting

Before:

<?php
return [
    'components' => [
        'log' => function() {
            $target = new \craft\log\MonologTarget(['name' => 'myTarget']);
            $target->getLogger()->setHandlers([
                (new \Monolog\Handler\StreamHandler('php://stderr', \Monolog\Logger::ERROR))
                    ->setFormatter($target->getFormatter()),
            ]);
        
            $dispatcher = new \craft\log\Dispatcher();
            $dispatcher->targets[] = $target;
        
            return $dispatcher;
        },
    ],
];

After:

<?php
// After
return [
    'components' => [
        'log' => [
            'targets' => [
                [
                    'class' => \craft\log\MonologTarget::class,
                    'name' => 'myTarget',
                    'logger' => fn(\craft\log\MonologTarget $target) => $target
                        ->getLogger()
                        ->setHandlers([
                            (new \Monolog\Handler\StreamHandler('php://stdout'))
                                ->setFormatter($target->getFormatter()),
                        ]
                    ),
                ]
            ]
        ],
    ],
];

…or, push a handler onto Craft's default log targets:

<?php
return [
    'components' => [
        'log' => [
            'monologTargetConfig' => [
                'logContext' => false,
                'logger' => fn(\craft\log\MonologTarget $target) => $target
                    ->getLogger()
                    ->pushHandler(
                        (new \Monolog\Handler\StreamHandler('php://stdout'))
                            ->setFormatter($target->getFormatter())
                    ),
            ],
        ],
    ],
];

[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).

[timkelty]

Adds getters for all these so they can be used in the Logger closure