Moves icons to the MintX theme, since that seems to be the default in Mint these days.
Uses newer, higher-quality renders of the PIA logo
Honestly I'm a little unsure of whether we should be creating additional links to these icons in the other icon themes or whether we should be throwing them into a 'default, fallback' icon theme or something. Haven't dealt with this side of GTK and icon themes much before so just let me know if I need to make any changes there, to ensure the icons stay available across the different icon themes.
So this PR does two things:
Honestly I'm a little unsure of whether we should be creating additional links to these icons in the other icon themes or whether we should be throwing them into a 'default, fallback' icon theme or something. Haven't dealt with this side of GTK and icon themes much before so just let me know if I need to make any changes there, to ensure the icons stay available across the different icon themes.