Add an InvokeOption for executing an Invoke at the root-module level.

[sywhang]

When writing fx.Modules, it may be desirable sometimes to be able to run the Invoke at the root-module level.

We can do this by exposing an InvokeOption that can be passed to fx.Invoke.

Internal Ref: GO-1676

[jkanywhere]

What is the expected difference in behavior between Invoke in an fx.Module vs Invoke at the root level?

Also, the internal ticket GO-1676 is closed Won't Do. Perhaps this issue should be closed as well?