feat: Allow skip check if dir is full or empty for icons

[mooreye]

I use Borg Backup. It can mount its repo with FUSE, and then you get a mountpoint directory with Borg archives as subdirs. However, accessing each directory is very time consuming, it takes me about a minute to cd or ls into one of them.

By using eza --icons=always when in the main mountpoint, eza freezes and even seems impossible to ctrl+c. I strongly suspect this is due to determining for each dir if a dir is empty or not, as they use different icons.

It would be beneficial to add a flag to eza that allows to skip this single check, and use the same icon for full and empty dirs. This would allow use cases like this to keep it aliased to eza --icons=auto ... while avoiding such performance penalties, by sacrificing a minor detail in dir icon.

[heftig]

Related: #1214