build: support pkg managers installation (#87)

closes #71, #84, #86
- AUR
- Homebrew
- Nix
- Debian (.deb)
- RPM (.rpm)
- Aqua
- ASDF

This is my first time doing this, so there might be mistakes. If you
can't download it through any pkg manager, please leave a comment or
open an issue

---------

Co-authored-by: use-the-fork <23747916+use-the-fork@users.noreply.github.com>

scripts/prerm.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+action="$1"
+if [ "$action" = "remove" ] || [ "$action" = "0" ]; then
+    echo ""
+    echo "========================================================================="
+    echo " WARNING: To completely remove IRIS configurations and shell hooks,"
+    echo " please run 'iris uninstall' BEFORE removing this package, or manually"
+    echo " clean up ~/.config/iris and your shell RC files (e.g. ~/.zshrc)."
+    echo "========================================================================="
+    echo ""
+fi