[Feature Request] Require indexed fields in findBy() and similar methods

[priyadi]

Forgetting to add an index is very common, and when that happens, we usually don't notice that until the app is already long in production.

I propose creating a PHPstan rule that ensures the existence of an index in these areas:

• criteria & orderBy parameters of findBy & similar methods
• where, orderBy, groupBy in QueryBuilder
• where and orderBy in Criteria