feat(index): Provide a similar API to Query (#9193)

**What**
Align the index engine API to be similar to the Query API

## Example

```ts
        // Benefit from the same level of typing like the remote query

        const { data, metadata } = await indexEngine.query<'product'>({
          fields: [
            "product.*",
            "product.variants.*",
            "product.variants.prices.*",
          ],
          filters: {
            product: {
              variants: {
                prices: {
                  amount: { $gt: 50 },
                },
              },
            },
          },
          pagination: {
            order: {
              product: {
                variants: {
                  prices: {
                    amount: "DESC",
                  },
                },
              },
            },
          },
        })
```

packages/modules/index/src/utils/flatten-object-keys.ts

@@ -0,0 +1,59 @@
+import { OPERATOR_MAP } from "./query-builder"
+
+/**
+ * Flatten object keys
+ * @example
+ * input: {
+ *   a: 1,
+ *   b: {
+ *     c: 2,
+ *     d: 3,
+ *   },
+ *   e: 4,
+ * }
+ *
+ * output: {
+ *   a: 1,
+ *   b.c: 2,
+ *   b.d: 3,
+ *   e: 4,
+ * }
+ *
+ * @param input
+ */
+export function flattenObjectKeys(input: Record<string, any>) {
+  const result: Record<string, any> = {}
+
+  function flatten(obj: Record<string, any>, path?: string) {
+    for (const key in obj) {
+      const isOperatorMap = !!OPERATOR_MAP[key]
+
+      if (isOperatorMap) {
+        result[path ?? key] = obj
+        continue
+      }
+
+      const newPath = path ? `${path}.${key}` : key
+
+      if (obj[key] === null) {
+        result[newPath] = null
+        continue
+      }
+
+      if (Array.isArray(obj[key])) {
+        result[newPath] = obj[key]
+        continue
+      }
+
+      if (typeof obj[key] === "object" && !isOperatorMap) {
+        flatten(obj[key], newPath)
+        continue
+      }
+
+      result[newPath] = obj[key]
+    }
+  }
+
+  flatten(input)
+  return result
+}