Add sample showing how to use aspire orchestration with WebApplicationFactory

[davidfowl]

See https://github.com/dotnet/aspire/pull/388

e.g https://github.com/dotnet/eShop/blob/main/tests/Catalog.FunctionalTests/CatalogApiFixture.cs

cc @ReubenBond

[josephaw1022]

@davidfowl I see the link links to a fix to the eshop tests. This a testing specific example? If so, the example for this issue could then be used for a tutorial in the documentation for a tutorial on "testing strategies" or something along those lines.