HandleCreateEC2CredentialSuccessfully creates an HTTP handler at `/users` on the test handler mux that tests application credential creation.

HandleDeleteEC2CredentialSuccessfully creates an HTTP handler at `/users` on the test handler mux that tests application credential deletion.

HandleGetEC2CredentialSuccessfully creates an HTTP handler at `/users` on the test handler mux that responds with a single application credential.

HandleListEC2CredentialsSuccessfully creates an HTTP handler at `/users` on the test handler mux that responds with a list of two applicationcredentials.

CreateRequest provides the input to a Create request.

GetOutput provides a Get result.

ListOutput provides a single page of EC2Credential results.

ExpectedEC2CredentialsSlice is the slice of application credentials expected to be returned from ListOutput.