Add a custom monolog formatter for Nutgram

[Lukasss93]

This PR adds a custom monolog formatter for Nutgram.
It's a simple formatter that shows the date, the message, the endpoint and the content/response.

Before this PR

.env file:

TELEGRAM_LOG_CHANNEL=stderr

After this PR

config/logging.php file:

// [...]
'channels' => [
    // [...]
    'nutgram' => [
        'driver' => 'monolog',
        'level' => env('LOG_LEVEL', 'debug'),
        'handler' => StreamHandler::class,
        'formatter' => NutgramFormatter::class,
        'with' => [
            'stream' => 'php://stderr',
        ],
        'processors' => [PsrLogMessageProcessor::class],
    ],
]

.env file:

TELEGRAM_LOG_CHANNEL=nutgram