add coverage for inverse futures private getter endpoints, migrate private getter methods to base class

src/util/requestUtils.ts

@@ -59,11 +59,18 @@ export function getRestBaseUrl(
 }
 
 export function isPublicEndpoint(endpoint: string): boolean {
-  if (endpoint.startsWith('v2/public')) {
-    return true;
-  }
-  if (endpoint.startsWith('public/linear')) {
-    return true;
+  const publicPrefixes = [
+    'v2/public',
+    'public/linear',
+    'spot/quote/v1',
+    'spot/v1/symbols',
+    'spot/v1/time',
+  ];
+
+  for (const prefix of publicPrefixes) {
+    if (endpoint.startsWith(prefix)) {
+      return true;
+    }
   }
   return false;
 }