This adds a new HttpState object which holds common http state(#10175). This reduces the amount of work that is required to add extra things to the Http state.
The HttpState object currently holds:
```
hsts_list: Arc::new(RwLock::new(HSTSList::new())),
cookie_jar: Arc::new(RwLock::new(CookieStorage::new())),
auth_cache: Arc::new(RwLock::new(HashMap::new())),
```
Source-Repo: https://github.com/servo/servo
Source-Revision: d82f97a9cd9f208a4f331d5991486ae7f0108c08
initial attempt of
- in resource_thread.rs, define an HTTP authorization cache storage (username, password, URL) and instantiate it like the cookie_storage member (inside an Arc<Rwlock<>> value, to enable sharing it between threads)
- in modify_request_headers in http_loader.rs, implement the remaining pieces of step 12(13?) of the appropriate specification using this new authorization cache.
for the NCSU student project Implement HTTP authorization UI and persistent sessions.
Source-Repo: https://github.com/servo/servo
Source-Revision: 7f944afee88bb2ab13de4f37118af14d40328f7f
Addresses both cookies in request and response. Resolves#9540.
Source-Repo: https://github.com/servo/servo
Source-Revision: bc034845b7e543e4e71fa21d6bf99e9f10ddb6c5
