Allow to customize the ModelNotFoundException per model

[Gummibeer]

The idea is a new method on the Model that returns a new instance of a ModelNotFoundException and the return has to be an instance of ModelNotFoundException to prevent breaking changes.
This method is called everywhere where the core throws a ModelNotFoundException - like firstOrFail(), findOrFail() ...

With that method, the user can create a new custom exception UserNotFoundException which is always thrown when a User model is not found.

Right now I'm doing this with the \Illuminate\Foundation\Exceptions\Handler::map() functionality. But having a method on the model would be more intuitive - like customizing the collection or query builder.

https://twitter.com/devgummibeer/status/1521093637123321858

[Gummibeer]

Notes / other Ideas:

• User::newNotFoundException($ids)
• ModelNotFoundException::forModel($class)
• User::query()->findOrThrow($id, new Exception)
• User::query()->findOrAbort($id, $code, $message, $headers)

[Gummibeer]

#42253