Support native validator

Nobody has claimed this yet.

# Feature request

### Context

As I see - mongo has [his own validation](https://www.mongodb.com/docs/manual/core/schema-validation/). I saw sources - nothing about mongo validator.

### Solution

It will be pretty, if i can set validator in my schema, for example

```
class CapitalCity(Model):
name: str
population: int

class Config:
collection = "city"
validator = {...}
```
or if validator generated, based on pydantic schema
```
CapitalCity.model_json_schema()
```

### Additional context

In my opinion, it can be set when collection and index created:
```
engine = AIOEngine()
await engine.configure_database([CapitalCity])
```

### Why we need it, besides of code validation now?

So, i can't have an ideal answer. For me, it's necessary, if we communicate with db - validate it on multiple sides - in code and in db. Same things happen with relation db in sqlalchemy and sqlmodel.

One more example - frontend validation in html forms plus backend validation in schemas/serializers

Start at AIOEngine.configure_database and inspect how the collection and indexes are created, then trace the model Config and model_json_schema entry points. Done means a schema can provide a MongoDB validator, or one can be generated from the Pydantic schema, and it is applied when the database is configured.

Written by the indexing model from the issue text.