Centralized configuration and dependency support through contexts

[Turnerj]

One area that is under developed is support for configuring the context and the MongoDbSets it creates. There should be settings on the context which are passed on through to a MongoDbSet which allow control of things like validation or whether navigation properties/entity relationships are enabled. Kinda like how MongoDB does it in the driver with MongoCollectionSettings and MongoDatabaseSettings.

Related to this, it is worth updating how entity mappers are created from the top of the tree (aka. context). Perhaps have an attribute like [Mapping(typeof(MyCustomEntityMapper))] to allow a user to control the actual mapping tool used.

[Turnerj]

After a lot more thinking and researching, EF Core seems to approach this problem the best through its options builder etc.

EF Core uses the Microsoft Dependency Injection library to do DI internally and I would be doing the same. What I don't want to do is require specifying contexts in a composition root if the person isn't using DI themselves.

Gonna need to think about this more as so far, it is a huge undertaking to make the code work due to little things like quirks with Entity Relationships.

[Turnerj]

Not a complete solution but the landing of #43 provides a common dependency (IMongoDbConnection) between various layers of the codebase. Additionally, there is control of DbSets through attributes (as seen by the MongoDbBucketSet plus access to DbSet initialisation through the context itself.

With that change, I will close this and open a new issue in the future once more flexibility is required.