style: fix whitespace issues in `popup-manager.tsx`

[agilgur5]

Motivation

Changes have been in my stash for a while are fairly noticeable

Modifications

• remove extra whitespace in import
• add lacking newlines in component JSX

Verification

Lint passes, pure whitespace change

Future Work

While adding prettier et al could be useful, probably not worth given that this repo is deprecated per #453