[icons] fix bookmark icons

- the bookmark icons were a bit off-centre, went ahead and trimmed most of their padding and made them centered
- made it so the solid version can also be used dynamically as the outlined version by targeting id="fill" with css and hiding it
- kept the outlined version in the library anyway in case we ever want to use it non-dynamically
- also ran prettier formatting on the file as it was hard to read

Author: SamusElderg