WIP: Add architecture constraints

[juliusstoerrle]

Here a proposal to add architecture checks using https://www.phpat.dev/, executed as phpstan extension.

Checks are seperated in:

• HighLevelArchitecture, some basic checks, basically on the structure of our namespaces
• CoreDomainLayers, limiting which components inside core can depend on others
• NamingConventions to enforce a pattern language

Currently checks are limited as component names are not finalised. Any checks besides those in the core that should be established?

• Add phpat to composer.lock file

[juliusstoerrle]

Potential checks within Core?

• Services only on model
• Services using interfaces
• Commands, events are POPOs

Checks within View:

• Controller using __invoke & Route Attribute
• Forms nicht auf Controller
• Requests nicht auf Form oder Controller -> POPO