Add Architecture Testing

[aidan-casey]

@vsergiu93 brought up the idea of architecture testing in #114. I think this is a great idea and something work exploring.

Looking at ta-tikoma/phpunit-architecture-test (which Pest uses) it does not appear they currently have support for attributes. It seems like that would be a pretty key thing considering discovery and validation rules.

There are some alternatives (phpat, etc.) that do support attributes and are probably worth digging into further.