Timber: Apply `maybe_convert_array` to all class functions in Timber\Twig

[jarednova]

As created in #1788, implement the maybe_convert_array method throughout Timber\Twig

https://github.com/timber/timber/blob/2.x/lib/Twig.php#L91-L93

$twig->addFunction( new Twig_Function( 'Attachment', function( $post_id, $attachment_class = 'Timber\Attachment' ) {
    return self::maybe_convert_array( $post_id, $attachment_class );
} ) );

[seancrater]

@jarednova Think this might be a decent first contribution? If so, want to keep running with pid as opposed to post_id for argument naming convention?

[jarednova]

def. post_id please! clarity > brevity

[seancrater]

I’m going to work this out tonight! Assuming the PR should be against the 2.x branch too 😉

[gchtr]

@seancrater Great! I think this issues makes a for a good first contribution! Yep, all issues that are marked with the 2.0 label should get a PR against the 2.x branch 👍. I’m looking forward to that pull request. Thanks in advance!

[seancrater]

Created that PR whenever you have a chance @gchtr and @jarednova, thanks!