The `object-curly-newline` rule made the assumption that the last token
is always `}`. However, when an object is typed with flow this is not
the case. This causes false positives, as described in babel/babel-eslint#513.

By adding a filter to the `getLastToken` function we skip over the flow
types, and get the actual closing brace. For symmetry the same filter is
added for the open brace, though I'm not aware of any issues it would
fix.

- Added tests for `object-curly-newline` in code annotated with flow types
- Fixed incorrect behaviour of object-curly-newline for literal object types

As per eslint#9458 (comment)