Enable usage of Route Groups for client generation

[dev-in-disguise]

When using controllers it is possible to use {controller} when setting stuff within the OpenApiProjectReference. We use that in our projects to set <ClassName>{controller}Client</ClassName>.

Since .NET 7 when using minimal apis we can now define so called route groups via app.MapGroup("GroupName") to group several endpoints together. When using this I would now like to have the possibility to define the ClassName in a similar fashion to what {controller} does. So e.g. a {routeGroup} which creates a client per route group.

By the way I'd gladly try to implement a first version if you think this would be a good and necessary addition.

[BalintHarmatAtBetssonGroup]

FYI I just needed this as well, and figured out we can hijack the {controller} pattern for it.

You just have to create an IDocumentFilter implementation for your swagger generator, that constructs the operationId parameter for each operation, in the form controller_method. Obviously since you don't have an actual controller class, and methods with minimal apis, you need to sanitize the tags of the operation into a valid class name (the group will show up as a tag on the operation) and divine a method name for it from the info of the operation.

Has lots of possible ugly edge cases around so I can't give a complete example, as didn't have time for it yet, but that is the gist of it.