[1.x] Adds `title` function

[nunomaduro]

This pull request addresses https://github.com/livewire/volt/issues/33, by allowing to set a title on the layout using the function title.

<?php

use function Livewire\Volt\{state, title};

title('custom title');

state(...);

// ...

?>

<div>
    <!-- template -->
</div>

Docs: https://github.com/livewire/livewire/pull/6517.

[jdion84]

You rock so hard dude