Ignore moment.js dependency for pikaday

What does this MR do?

Pikaday has a dependency on moment.js but moment.js was removed from our codebase and build outputs an error in the browser's console. Potential fix is to wait when upstream removes moment.js as a direct dependency but Pikaday looks unmaintained (last commit in 2018). Another fix is to add IgnorePlugin from webpack to ignore moment.js when processing Pikaday. That missing dependency also breaks source maps.

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