If the old lifecycle hooks (componentWillMount, componentWillUpdate, componentWillReceiveProps) are detected, these methods will be called and a deprecation warning will be logged. (In other words, we do not check for both the presence of the old and new lifecycles.) This commit is expected to fail tests.

This should handle the bulk of the updates. I will manually update TypeScript and CoffeeScript tests with another commit.
The actual command run with this commit was: jscodeshift --parser=flow -t ../react-codemod/transforms/rename-unsafe-lifecycles.js ./packages/**/src/**/*.js

Explaining why lifecycles hooks have not been renamed in this test.

Also added a new set of tests focused on server side lifecycle hooks.

Also added warnings for several cases involving getDerivedStateFromProps() as well as the deprecated lifecycles.
Also added tests for the above.

Also updated class component and lifecyle tests to cover the added functionality.

Updated tests accordingly, by temporarily splitting tests that were specific to this feature-flag into their own, internal tests. This was the only way I knew of to interact with the feature flag without breaking our build/dist tests.

Replaced 'You may may have returned undefined.' with 'You may have returned undefined.'

This value will be either workInProgress.memoizedState (for updates) or instance.state (for initialization).

…ateFromProps.

And added some new tests for this change.

Also:
* Improved a couple of falsy null/undefined checks to more explicitly check for null or undefined.
* Made some small tweaks to ReactFiberClassComponent WRT when and how it reads instance.state and sets to null.

Also add support for new static getDerivedStateFromProps method