Add react-lifecycle-compat to external array in rollup config

[petermikitsh]

Are you submitting a bug report or a feature request?

Bug report. (Debatably so).

What is the current behavior?

react-lifecycle-compat is inlined into the ES Module build. (Also the case for the commonjs build).

What is the expected behavior?

react-lifecycle-compat is imported via import or require (for the module build and commonjs builds, respectively).

What's your environment?

Latest React Final Forms Array, Final Form Arrays, and Final Form.

Other information

For reasons outlined in reactjs/react-lifecycles-compat#31, I'm using react-final-form-arrays with Preact, and I'm going to need to shim react-lifecycle-compat to something else. Difficult to do that when it is inlined :)