Apps: Remove unused

Removed:
- Chrome extension symlinks (no longer available in Chrome Web Store)
- hwbrowser (discontinued 2013, renamed to hardinfo to replace the symlink)
- hwinfo (command line tool, doesn't use icon that I can find)
- Hulu Desktop (dicontinued 2013)
- Gmail symlinks (all these apps seem to be no longer developed/available for many years)
- Gmail (Not use directly for anything, if needed we should use the new Gmail logo)
- Google Hangouts (shutdown by Google in 2020)
- Google Plus (shutdown by Google in 2019)
- Miro and Miro Browser (Final release in 2013)
- x-pdf (wrong name, kept `xpdf`)

Updated:
- hardinfo (no longer a symlink to hwbrowser, update gradients/palette/borders)