chore: move fn-in-array to common-functions

This is used by all generic `set` commands, so we should just make it globally available.

plugins/common/functions

@@ -957,6 +957,16 @@ is_val_in_list() {
   echo "$val_in_list"
 }
 
+fn-in-array() {
+  declare desc="return true if value ($1) is in list (all other arguments)"
+
+  local e
+  for e in "${@:2}"; do
+    [[ "$e" == "$1" ]] && return 0
+  done
+  return 1
+}
+
 remove_val_from_list() {
   declare desc="remove value ($1) from list ($2) separated by delimiter ($3) (delimiter defaults to comma) and return list"
   local value="$1" list="$2" delimiter="${3:-,}"