[10.x] Add displayName for queued Artisan commands

[jessarcher]

This PR adds a displayName method for commands queued using the Artisan::queue method that allows the underlying command name to be used for display purposes.

This matches other queued wrappers:

• framework/src/Illuminate/Events/CallQueuedListener.php

  Lines 159 to 167 in a47df68

  	/**
  	* Get the display name for the queued job.
  	*
  	* @return string
  	*/
  	public function displayName()
  	{
  	return $this->class;
  	}

• framework/src/Illuminate/Queue/CallQueuedClosure.php

  Lines 100 to 111 in a47df68

  	/**
  	* Get the display name for the queued job.
  	*
  	* @return string
  	*/
  	public function displayName()
  	{
  	$reflection = new ReflectionFunction($this->closure->getClosure());
  	return 'Closure ('.basename($reflection->getFileName()).':'.$reflection->getStartLine().')';
  	}
  	}

• framework/src/Illuminate/Mail/SendQueuedMailable.php

  Lines 121 to 129 in a47df68

  	/**
  	* Get the display name for the queued job.
  	*
  	* @return string
  	*/
  	public function displayName()
  	{
  	return get_class($this->mailable);
  	}

• framework/src/Illuminate/Notifications/SendQueuedNotifications.php

  Lines 115 to 123 in a47df68

  	/**
  	* Get the display name for the queued job.
  	*
  	* @return string
  	*/
  	public function displayName()
  	{
  	return get_class($this->notification);
  	}