feat(pepicons.com): allow for multiple categories

steps to start implementing:
1. add a new folder called `[sound|arrows]pop` at `packages/pepicons/export/`
2. move `packages/pepicons/export/[sound]pop/repeat_audio_media-controls_music.svg`
to this new folder
3. `npm i && npm run build`
4. you'll see that `sound|arrows` is treated as one category. Now the entire pipeline needs to be updated to cover both categories as single categories
5. as for the front-end `npm run dev:pepicons.com`, the icon needs to show up in both categories