Posix command wrappers

[albert-tomanek]

I've written some wrapper functions for common linux commands like df and flatpak list that parse their output. They're not aliases per-se, but that seemed to be the closest directory for them so I've put them into aliases/posix/.

I've also added a module containing my functions for modifying filesystem tags, comments, and ratings in modules/fsattr/.

[fdncred]

Since these are almost all export def that puts them in the module category. You should probably just put them all in one file and make a folder called posix_cmds or something like that with a mod.u and a readme.md describing what it is. it definitely doesn't belong in aliases.