[3.x] Ability to review Exception context data

[crynobone]

Current behaviour

When developer use custom report and log an error manually using the following:

<?php

namespace App\Exceptions;

class TestException extends \Exception
{
    public function report()
    {
        \Log::error($this->getMessage(), [
            'message' => 'Context message here',
            'path' => base_path(),
            'exception' => $this,
        ]);
    }
}

We should be able to see the custom context. However at the moment only message, location and stacktrace can be reviewed from Telescope.

Excepted Behaviour

Exception without any custom context should remain the same as before.

Exception with custom context should be able to show the context.

Solves #875

[taylorotwell]

Thanks