Alias alternatives to common unix commands

[tmr08c]

I have started trying out new versions of various standard unix-y commands. I'd like to set up my dotfiles to, if the alternatives exist, use them instead of the defaults.

Examples:

• cat --> bat
  • The bat README has a section on auto-switching color scheme based on system dark mode. We could use that or try to leverage our darkMode() function
• ls --> exa
• grep --> rg (or ag)
• find --> fd
• (maybe) https://github.com/dalance/procs instead of ps
  • There may be default permission concerns that aren't worth messing with