Ability to create indexes from Meta class implementation

[RamiAwar]

🚀 Feature Request

Add indexes to internal metadata class to enable easy index creation.

class UserRepository(BaseRepository): class Meta: model = User collection = "user" indexes = [ { fields: ["username"], unique: True } ]

🔈 Motivation

Being a PyMongo wrapper, this is a deal-breaker for anyone who needs to use Mongomantic in production.

🛰 Alternatives

Use PyMongo, but if Mongomantic was good then users shouldn't have to.