fix(api): align Swagger schemas for UserSettings and TopicListResponse (#38590)

Corrects the Swagger/OpenAPI schemas for `/user/settings` and
`/topics/search` to match the actual JSON objects returned by the API.

Signed-off-by: Sudhanshu Singh <sudhanshuwriterblc@gmail.com>

modules/structs/repo_topic.go

@@ -32,3 +32,8 @@ type RepoTopicOptions struct {
 	// list of topic names
 	Topics []string `json:"topics"`
 }
+
+// TopicListResponse returns a list of TopicResponse
+type TopicListResponse struct {
+	Topics []*TopicResponse `json:"topics"`
+}