Improve readability of list command

Display the default key length of domain certificates when listing certificates if no key length is explicitly set. Wrap value in square brackets to indicate default value, or double quotes to indicate an explicit value.

acme.sh

@@ -4534,7 +4534,12 @@ list() {
         _initpath "$d" "$_isEcc"
         if [ -f "$DOMAIN_CONF" ]; then
           . "$DOMAIN_CONF"
-          printf "%s\n" "$Le_Domain${_sep}\"$Le_Keylength\"${_sep}$Le_Alt${_sep}$Le_CertCreateTimeStr${_sep}$Le_NextRenewTimeStr"
+          if [ -z "$Le_Keylength" ]; then
+            local Le_HR_Key_Length="[$DEFAULT_DOMAIN_KEY_LENGTH]"
+          else
+            local Le_HR_Key_Length="\"$Le_Keylength\""
+          fi
+          printf "%s\n" "$Le_Domain${_sep}$Le_HR_Key_Length${_sep}$Le_Alt${_sep}$Le_CertCreateTimeStr${_sep}$Le_NextRenewTimeStr"
         fi
       )
     done