type JsThreadServiceCallback = Option<unsafe extern "system" fn(_: JsBackgroundWorkItemCallback, _: *mut c_void) -> bool>;
A thread service callback.
The host can specify a background thread service when calling JsCreateRuntime. If
specified, then background work items will be passed to the host using this callback. The
host is expected to either begin executing the background work item immediately and return
true or return false and the runtime will handle the work item in-thread.
The callback for the background work item.
The data argument to be passed to the callback.