fix(typescript): stable parens for function type in arrow return type

[ikatyang]

Fixes #5789

• I’ve added tests to confirm my change works.
• (If changing the API or CLI) I’ve documented the changes I’ve made (in the docs/ directory)
• (If not an internal change) I’ve added my changes to the CHANGELOG.unreleased.md file following the template.
• I’ve read the contributing guidelines.

✨Try the playground for this PR✨

[VincentLanglet]

I tested
const foo = (): (() => void) => (): void => null;
const bar = (): () => void => (): void => null;
const baz = (): ((() => void)) => (): void => null;

And
class Foo {
foo: (() => void)
}

In the playground, and it works well