Add values for all prettier configuration options

[nickvisut]

Our prettier config currently explicitly lists three properties, which would override any defaults.

To head off issues w/future breaking changes to config default values*, we could explicitly set all remaining properties in our config (.prettierrc.json).

*we encountered this when upgrading Storybook, which had prettier as a transitive dependency that conflicted w/our own.

See #438 (comment) for context.