Refactor qmk_install.sh (#10681)

util/install/slackware.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+_qmk_install_prepare() {
+    echo "Before you continue, please ensure that your user is added to sudoers and that sboinstall is configured."
+    read -p "Proceed? [y/N] " res
+
+    case $res in
+        [Yy]*)
+            ;;
+        *)
+            return 1;;
+    esac
+}
+
+_qmk_install() {
+    echo "Installing dependencies"
+
+    sudo sboinstall \
+        avr-binutils avr-gcc avr-libc \
+        arm-binutils arm-gcc newlib \
+        python3 \
+        avrdude dfu-programmer dfu-util teensy_loader_cli
+
+    python3 -m pip install --user -r $QMK_FIRMWARE_DIR/requirements.txt
+}