Handle DOKKU_FORCE_TTY in has_tty function

plugins/common/functions

@@ -4,6 +4,10 @@ set -eo pipefail
 
 has_tty() {
   declare desc="return 0 if we have a tty"
+  if [[ "$DOKKU_FORCE_TTY" == "true" ]]; then
+    return 0
+  fi
+
   if [[ "$DOKKU_DISABLE_TTY" == "true" ]]; then
     return 1
   fi