use steams own avatar cache

[sahin-a]

apparently steam has it's own avatar cache where each image files name is the steam id of the corresponding user.

Fallback to steams cache when the switchers avatar cache fails. I guess we could also remove the custom avatar handling code but we wouldn't have up to date avatars for accounts that haven't been logged in to for a long time,

Also, who doesn't have internet access in 2023. People with up2date steam avatar cache but outdated switcher avatar cache just have to feel the pain then ain't worth the effort adding extra logic which decides whos more up2date