Fix compilation errors in cookie_jar branch

This commit fixes multiple compilation errors introduced by the refactoring:

1. Added missing http_client_conn_free() helper function
2. Fixed cookie_jar reference (cookie_jar->count to client->cookie_jar.count)
3. Restored missing HTTP_ClientConn fields: handle, client, and url
4. Fixed undefined 'conn' variable in http_client_get_builder (changed to 'i')
5. Fixed incorrect field reference (entry.domain.len to domain.len)
6. Added missing closing parenthesis in should_send_cookie
7. Removed duplicate 'path' variable declaration
8. Fixed cookie jar access to use builder.client instead of conn->client
9. Fixed byte_queue_write calls to use .ptr and .len instead of HTTP_String structs
10. Fixed missing -> operators in url_to_connect_target
11. Fixed undefined 'url' variable by using conn->url
12. Fixed headers[i].value to set_cookie.value in save_one_cookie
13. Fixed typo: antry to entry
14. Fixed save_one_cookie parameter type (headers[i] instead of headers[i].value)
15. Fixed print_bytes calls to create HTTP_String structs
16. Added logic to store socket handle when connection is established
17. Updated http_client_get_builder signature to return HTTP_RequestBuilder
18. Updated simple_client.c example to match new API

examples/simple_client.c

@@ -12,9 +12,7 @@ int main(void)
     if (http_client_init(&client) < 0)
         return -1;
 
-    HTTP_RequestBuilder builder;
-    if (http_client_get_builder(&client, NULL, &builder) < 0)
-        return -1;
+    HTTP_RequestBuilder builder = http_client_get_builder(&client);
 
     http_request_builder_url(builder,
         HTTP_METHOD_GET,
@@ -49,7 +47,8 @@ int main(void)
             return -1;
 
         HTTP_Response *response;
-        while (http_client_next_response(&client, &response)) {
+        void *user;
+        while (http_client_next_response(&client, &response, &user)) {
             // TODO
             http_free_response(response);
         }