Run the executor bootstrapping the execution with the provided future.
This creates a new
CurrentThread executor, spawns the provided future,
and blocks the current thread until the provided future and all
subsequently spawned futures complete. In other words:
- If the provided bootstrap future does not spawn any additional tasks,
- If the provided bootstrap future does spawn additional tasks, then
block_on_allreturns once all spawned futures complete.
See module level documentation for more details.