Remove custom WebSocket code (#4001)

* Remove custom WebSocket code

Remove our custom WebSocket code and only use the Rocket code.
Removed all options in regards to WebSockets
Added a new option `WEBSOCKET_DISABLED` which defaults too `false`.
This can be used to disable WebSockets if you really do not want to use it.

* Addressed remarks given and some updates

- Addressed comments given during review
- Updated crates, including Rocket to the latest merged v0.5 changes
- Removed an extra header which should not be sent for websocket connections

* Updated suggestions and crates

- Addressed the suggestions
- Updated Rocket to latest rc4
  Also made the needed code changes
- Updated all other crates
  Pinned `openssl` and `openssl-sys`

---------

Co-authored-by: Daniel García <dani-garcia@users.noreply.github.com>

src/main.rs

@@ -52,7 +52,7 @@ mod ratelimit;
 mod util;
 
 use crate::api::purge_auth_requests;
-use crate::api::WS_ANONYMOUS_SUBSCRIPTIONS;
+use crate::api::{WS_ANONYMOUS_SUBSCRIPTIONS, WS_USERS};
 pub use config::CONFIG;
 pub use error::{Error, MapResult};
 use rocket::data::{Limits, ToByteUnit};
@@ -497,7 +497,7 @@ async fn launch_rocket(pool: db::DbPool, extra_debug: bool) -> Result<(), Error>
         .register([basepath, "/api"].concat(), api::core_catchers())
         .register([basepath, "/admin"].concat(), api::admin_catchers())
         .manage(pool)
-        .manage(api::start_notification_server())
+        .manage(Arc::clone(&WS_USERS))
         .manage(Arc::clone(&WS_ANONYMOUS_SUBSCRIPTIONS))
         .attach(util::AppHeaders())
         .attach(util::Cors())