Summary

• Get rid of /src/qt/assets/86box.png by replacing its only remaining use with an .ico matching the build type
• Remove unused 16x16 icons that were likely left over from early manager iterations
• Fix the floppy icons in the status bar changing to ZIP disk if a removable disk drive is present

Checklist

• Closes #xxx
• I have tested my changes locally and validated that the functionality works as intended
• I have discussed this with core contributors already
• This pull request requires changes to the ROM set
• This pull request requires changes to the asset set

References

N/A