Add DbGate support for MongoDB

[Alirexaa]

**Contributes to #415 **

PR Checklist

• Created a feature/dev branch in your fork (vs. submitting directly from a commit on main)
• Based off latest main branch of toolkit
• New integration
  • Docs are written
  • Added description of major feature to project description for NuGet package (4000 total character limit, so don't push entire description over that)
• Tests for the changes have been added (for bug fixes / features) (if applicable)
• Contains NO breaking changes
• Every new API (including internal ones) has full XML docs
• Code follows all style conventions

Other information

[Alirexaa]

Running the Postgres-ext example causes multiple DbGate containers to spin up—one for Postgres and another for MongoDB.

This occurred because we shared and compiled DbGateContainerResource.cs in two projects. This means these types are not what we expected(as same or equal type), as they have different assemblies. Therefore, the following code does not function as intended.

        //The `else` branch will be hit because DbGateContainerResource is not the same.
        if (builder.Resources.OfType<DbGateContainerResource>().SingleOrDefault() is { } existingDbGateResource)
        {
            var builderForExistingResource = builder.CreateResourceBuilder(existingDbGateResource);
            return builderForExistingResource;
        }
        else
        {
            var dbGateContainer = new DbGateContainerResource(name);
            var dbGateContainerBuilder = builder.AddResource(dbGateContainer)
                                               .WithImage(DbGateContainerImageTags.Image, DbGateContainerImageTags.Tag)
                                               .WithImageRegistry(DbGateContainerImageTags.Registry)
                                               .WithHttpEndpoint(targetPort: 3000, port: port, name: DbGateContainerResource.PrimaryEndpointName)
                                               .ExcludeFromManifest();

            return dbGateContainerBuilder;
        }

@aaronpowell, I suggest adding CommunityToolkit.Aspire.Hosting.DbGate and placing these shared files there.

[aaronpowell]

Ah yes, that's a really good point.

You're right, we're going to need to create that package for the shared types.

[Alirexaa]

@aaronpowell PR is ready for review.

[aaronpowell]

Just a question on the README

[aaronpowell]

Should we just provide a mostly empty README since this is a package that isn't really designed for direct consumption?

[Alirexaa]

We can not pack the packages with an empty README, but I updated the README to indicate that this package is designed for internal consumption.

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
Aspire.Hosting.MongoDB	38%	19%	136	❌
CommunityToolkit.Aspire.EventStore	100%	100%	46	✔
CommunityToolkit.Aspire.GoFeatureFlag	100%	97%	74	✔
CommunityToolkit.Aspire.Hosting.ActiveMQ	70%	27%	144	➖
CommunityToolkit.Aspire.Hosting.ActiveMQ.MassTransit	1%	0%	14	❌
CommunityToolkit.Aspire.Hosting.Azure.DataApiBuilder	100%	100%	22	✔
CommunityToolkit.Aspire.Hosting.Azure.StaticWebApps	100%	100%	28	✔
CommunityToolkit.Aspire.Hosting.Bun	81%	71%	54	✔
CommunityToolkit.Aspire.Hosting.Dapr	60%	51%	560	➖
CommunityToolkit.Aspire.Hosting.Dapr.AzureRedis	93%	71%	54	✔
CommunityToolkit.Aspire.Hosting.DbGate	63%	11%	62	➖
CommunityToolkit.Aspire.Hosting.Deno	84%	75%	72	✔
CommunityToolkit.Aspire.Hosting.EventStore	90%	71%	62	✔
CommunityToolkit.Aspire.Hosting.GoFeatureFlag	59%	11%	62	❌
CommunityToolkit.Aspire.Hosting.Golang	94%	50%	16	✔
CommunityToolkit.Aspire.Hosting.Java	69%	72%	120	➖
CommunityToolkit.Aspire.Hosting.Meilisearch	61%	27%	94	➖
CommunityToolkit.Aspire.Hosting.MongoDB.Extensions	65%	38%	80	➖
CommunityToolkit.Aspire.Hosting.Ngrok	59%	50%	58	❌
CommunityToolkit.Aspire.Hosting.NodeJS.Extensions	90%	68%	92	✔
CommunityToolkit.Aspire.Hosting.Ollama	65%	64%	198	➖
CommunityToolkit.Aspire.Hosting.PapercutSmtp	92%	50%	10	✔
CommunityToolkit.Aspire.Hosting.PostgreSQL.Extensions	70%	45%	88	➖
CommunityToolkit.Aspire.Hosting.Python.Extensions	69%	50%	86	➖
CommunityToolkit.Aspire.Hosting.RavenDB	64%	49%	176	➖
CommunityToolkit.Aspire.Hosting.Rust	94%	83%	16	✔
CommunityToolkit.Aspire.Hosting.SqlDatabaseProjects	74%	61%	114	➖
CommunityToolkit.Aspire.Hosting.Sqlite	96%	96%	38	✔
CommunityToolkit.Aspire.MassTransit.RabbitMQ	100%	100%	30	✔
CommunityToolkit.Aspire.Meilisearch	97%	92%	68	✔
CommunityToolkit.Aspire.Microsoft.Data.Sqlite	89%	85%	52	✔
CommunityToolkit.Aspire.Microsoft.EntityFrameworkCore.Sqlite	50%	50%	88	❌
CommunityToolkit.Aspire.OllamaSharp	87%	82%	68	✔
CommunityToolkit.Aspire.RavenDB.Client	60%	53%	237	➖
Summary	71% (4762 / 6715)	55% (1432 / 2610)	3119	➖

Minimum allowed line rate is 60%