feat(rcs): migrate all RCS APIs from rainyun-go-sdk

- 35 endpoints across 14 files, response structs split for reuse
- Reuse RcsRecord/Node/Plan/OsInfo/UsageData across list/detail/create
- Fix source bugs: {id} path placeholders, missing / in firewall pos path,
  missing body in ChargeRcsTrafic, resp vs &resp
- Add HTTPMethod_PATCH, common.BasicOperationResponse, VncConnectionInfo

constant/method.go

@@ -7,4 +7,5 @@ const (
 	HTTPMethod_POST   HTTPMethod = "POST"
 	HTTPMethod_DELETE HTTPMethod = "DELETE"
 	HTTPMethod_PUT    HTTPMethod = "PUT"
+	HTTPMethod_PATCH  HTTPMethod = "PATCH"
 )