feat(fmt): remove some unnecessary parens in types

[dsherret]

Before:

type Test = (string | number);

After:

type Test = string | number;

Also fixes an edge case of someone having a back slash as the last character in a JSX string literals (which work differently than regular string literals 🙄):

// should format as-is, but previously removed the back slash
const t = <div prop="\" />;