fix: register MongoDB AWS authentication for Atlas IAM (driver 3.x)

[sinadarbouy]

Summary

Fixes startup failure when MongoDB is configured with Atlas IAM authentication (authMechanism=MONGODB-AWS).

Adds the MongoDB.Driver.Authentication.AWS package and registers the AWS auth provider in MongoClientFactory.Create().

Problem

Starting with MongoDB .NET Driver 3.0, MONGODB-AWS was moved out of the core driver into an optional package and must be registered explicitly. Squidex uses driver 3.x but does not register the extension, so Atlas IAM connection strings fail at startup.

Example connection string:
mongodb+srv://cluster.example.mongodb.net/?authSource=%24external&authMechanism=MONGODB-AWS

Error without this change

MongoDB.Driver.MongoConnectionException: An exception occurred while opening a connection to the server. ---> System.NotSupportedException: Unable to create an authenticator. at MongoDB.Driver.MongoCredential.ToAuthenticator(...) at MongoDB.Driver.Core.Connections.ConnectionInitializer.CreateAuthenticator(...) ... at Squidex.Hosting.InitializerHost.StartAsync(...)

The application never becomes ready.

Root cause

Driver 2.x included MONGODB-AWS in the core package. Driver 3.x requires:

1. Package reference: MongoDB.Driver.Authentication.AWS (version aligned with MongoDB.Driver)
2. One-time registration: MongoClientSettings.Extensions.AddAWSAuthentication()

Without (2), the driver cannot resolve the SASL mechanism from the connection string.

Changes

• Squidex.Data.MongoDb.csproj — add MongoDB.Driver.Authentication.AWS 3.8.0
• MongoClientFactory.cs — register AWS authentication once before creating a MongoClient

All Mongo clients in Squidex go through MongoClientFactory.Create() (via ServiceExtensions).

Test plan

• Verified on EKS with Atlas IAM connection string and IRSA
• Application starts; /healthz and /readiness return 200
• No Unable to create an authenticator in logs

References

• MongoDB C# Driver — AWS IAM Authentication
• MongoDB .NET Driver 3.0 release notes (CSHARP-4911)

[sinadarbouy]

Hi @SebastianStehle , could you please take a look at this PR when you have a chance? Thank you!