Add model name mapping to swift5 client generator (#18780)

Author: oslTrifork

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift5ClientCodegen.java

@@ -717,6 +717,11 @@ public boolean isDataTypeBinary(final String dataType) {
      */
     @Override
     public String toModelName(String name) {
+
+        if (modelNameMapping.containsKey(name)) {
+            return modelNameMapping.get(name);
+        }
+
         // FIXME parameter should not be assigned. Also declare it as "final"
         name = sanitizeName(name);