fix typo: 'Resovling' -> 'Resolving'

tensorflow_federated/python/core/framework/__init__.py

...w_federated/python/core/impl/executors/executor_stacks.py

...derated/python/core/impl/executors/executor_utils_test.py

.../core/impl/executors/federated_composing_strategy_test.py

...ython/core/impl/executors/federated_resolving_strategy.py

.../core/impl/executors/federated_resolving_strategy_test.py

...ed/python/core/impl/executors/federating_executor_test.py

.../core/impl/executors/reference_resolving_executor_test.py

...thon/examples/remote_execution/remote_executor_example.py