feat: use a medium format (json/yaml/toml) to store icons information for different extension/filename/pattern

[Freed-Wu]

Comes from ogham/exa#1138:

It is easier to edit even for those contributors is not familiar with rust https://github.com/eza-community/eza/blob/afe832b943d328a20f43c6fa69dd8588cf3285ef/src/output/icons.rs
It is easier to compare the difference between this project's icon and other projects which provide icon display, so we can add icons more easily. Such as https://github.com/lambdalisue/nerdfont.vim/blob/master/assets/json/extension.json
It is easier to sort json by some programs like jq in CI/CD

Just my 2c, TIA!

[MartinFillon]

This needs to be discussed

[cafkafk]

My immediate thoughts is that this shouldn't create any performance regression, currently the icons are in a perfect hashmap created at compile time. So maybe this could exist for a user config? But it still would probably be kinda slow.

[MartinFillon]

That is why I would prefer, if we want to add better readability to put them in an enum so that we don't loose speed