Support IgnorePlurals and RemoveStopWords

[bpicolo]

These can either be a boolean (true/false) or array of string. Unfortunately terraform doesn't provide a direct way to support multiple-typed values.

A couple options I'm thinking of:

1. Created two separate fields (ignore_plurals, ignore_plurals_words) that enable/disable the functionality vs change the words inside.
2. Create some nested type that supports either/or
3. Map the concept of empty array to false and nil to true? (Not entirely sure if terraform will provide nil vs the empty array for the value if not specified. If it provides the empty array this is a no-go)