Remove icons for apps which don't want them

[clefebvre]

Some apps specifically asked not to be themed:

https://stopthemingmy.app

As much as possible this should be respected and icons for these apps should be removed from our themes.

From the website above I made the following list to keep track of this:

• [x] authenticator
• [x] aviator
• [x] blanket
• [x] blurble
• [x] bottles
• [x] citations
• [x] contrast
• [x] decoder
• [x] dialect
• [x] feedreader
• [x] fractal
• [x] fragments
• [x] fretboard
• [x] geary
• [x] generator
• [x] gradience
• [x] gradio
• [x] graphs
• [x] Highscore
• [x] icon library
• [x] icon preview
• [x] khronos
• [x] lollypop
• [x] lorem
• [x] newsflash
• [x] obfuscate
• [x] organizer
• [x] password-safe
• [x] pika backup
• [x] pitivi
• [x] podcasts
• [x] random
• [x] remotely
• [x] secrets
• [x] share preview
• [x] shortwave
• [x] teleport
• [x] timetrack
• [x] uberwriter
• [x] webfont kit

[clefebvre]

Only 4 apps had icons in Mint-Y, they'll be removed.