feat: allow API checkRequired middleware error to be internationalized

public/language/en-GB/error.json

@@ -2,6 +2,7 @@
 	"invalid-data": "Invalid Data",
 	"invalid-json": "Invalid JSON",
 	"array-expected": "A value of type Array was expected for property `%1`, but %2 was received instead",
+	"required-parameters-missing": "Required parameters were missing from this API call: %1",
 
 	"not-logged-in": "You don't seem to be logged in.",
 	"account-locked": "Your account has been locked temporarily",

src/middleware/index.js

@@ -255,5 +255,5 @@ middleware.checkRequired = function (fields, req, res, next) {
 		return next();
 	}
 
-	controllers.helpers.formatApiResponse(400, res, new Error(`Required parameters were missing from this API call: ${missing.join(', ')}`));
+	controllers.helpers.formatApiResponse(400, res, new Error(`[[error:required-parameters-missing, ${missing.join(' ')}]]`));
 };