feat(osx): add freespace command to clean purgeable disk space (#8762)

Co-authored-by: Marc Cornellà <hello@mcornella.com>

plugins/osx/osx.plugin.zsh

@@ -233,6 +233,29 @@ function rmdsstore() {
   find "${@:-.}" -type f -name .DS_Store -delete
 }
 
+# Erases purgeable disk space with 0s on the selected disk
+function freespace(){
+  if [[ -z "$1" ]]; then
+    echo "Usage: $0 <disk>"
+    echo "Example: $0 /dev/disk1s1"
+    echo
+    echo "Possible disks:"
+    df -h | awk 'NR == 1 || /^\/dev\/disk/'
+    return 1
+  fi
+
+  echo "Cleaning purgeable files from disk: $1 ...."
+  diskutil secureErase freespace 0 $1
+}
+
+_freespace() {
+  local -a disks
+  disks=("${(@f)"$(df | awk '/^\/dev\/disk/{ printf $1 ":"; for (i=9; i<=NF; i++) printf $i FS; print "" }')"}")
+  _describe disks disks
+}
+
+compdef _freespace freespace
+
 # Music / iTunes control function
 source "${0:h:A}/music"