Execute a service belonging to a page. This call errors if the servcice in the model is not available. Pages can only be executed when the service is running for a page.

Example:

// Call service "rpc_test" which adds and multiplies the numbers 1 and 1
let res = exo::rpc_page("rpc_test", [1, 1]).await?;
assert_eq!([2, 1], res);