Add typed DB entities based on PHP reflection

[ChristophWurst]

Resolves: n/a

Summary

Right now columns of a type other than string need to be refined using Entity::addType, typically from the Entity constructor. We can derive this information from typed properties in PHP7.4+ and the help of reflection.

Combined with constructor property promostion in PHP8.0+ entities can be as simple as

class Foo extends TypedEntity {
    public function __construct(
        protected int $id, 
        protected string $bar, 
        protected float $x,
        protected float $y,
    ) {}
}

While having PHPs full type support and automatic database type conversion.

The reason why I haven't added this feature into the existing Entity is that it has to be done in the constructor and Entity has none. https://en.wikipedia.org/wiki/Fragile_base_class

TODO

• Add TypedEntity
• Tests

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)