feat: Promote rpxy-lib/sticky-cookie to top-level feature

.. and fix compile warnings when disabled

rpxy-lib/src/message_handler/handler_main.rs

@@ -6,7 +6,7 @@ use super::{
   utils_request::InspectParseHost,
 };
 use crate::{
-  backend::{BackendAppManager, LoadBalanceContext},
+  backend::BackendAppManager,
   error::*,
   forwarder::{ForwardRequest, Forwarder},
   globals::Globals,
@@ -25,7 +25,7 @@ use tokio::io::copy_bidirectional;
 /// Context object to handle sticky cookies at HTTP message handler
 pub(super) struct HandlerContext {
   #[cfg(feature = "sticky-cookie")]
-  pub(super) context_lb: Option<LoadBalanceContext>,
+  pub(super) context_lb: Option<crate::backend::LoadBalanceContext>,
   #[cfg(not(feature = "sticky-cookie"))]
   pub(super) context_lb: Option<()>,
 }

rpxy-lib/src/message_handler/utils_headers.rs

@@ -3,7 +3,7 @@ use crate::{
   backend::{UpstreamCandidates, UpstreamOption},
   log::*,
 };
-use anyhow::{anyhow, ensure, Result};
+use anyhow::{anyhow, Result};
 use bytes::BufMut;
 use http::{header, HeaderMap, HeaderName, HeaderValue, Uri};
 use std::{borrow::Cow, net::SocketAddr};
@@ -22,6 +22,8 @@ pub(super) fn takeout_sticky_cookie_lb_context(
   headers: &mut HeaderMap,
   expected_cookie_name: &str,
 ) -> Result<Option<LoadBalanceContext>> {
+  use anyhow::ensure;
+
   let mut headers_clone = headers.clone();
 
   match headers_clone.entry(header::COOKIE) {