feature: Implement gateway ratelimit (#1537)

* Implement gateway ratelimit

* Remove unused code

* Share WebSocketRequestQueue between clients

* Add global limit and a way to change gateway limits

* Refactoring variable to fit lib standards

* Update xml docs

* Update xml docs

* Move warning to remarks

* Remove specific RequestQueue for WebSocket and other changes

The only account limit is for identify that is dealt in a different way (exclusive semaphore), so websocket queues can be shared with REST and don't need to be shared between clients anymore.

Also added the ratelimit for presence updates.

* Add summary to IdentifySemaphoreName

* Fix spacing

* Add max_concurrency and other fixes

- Add session_start_limit to GetBotGatewayResponse
- Add GetBotGatewayAsync to IDiscordClient
- Add master/slave semaphores to enable concurrency
- Not store semaphore name as static
- Clone GatewayLimits when cloning the Config

* Add missing RequestQueue parameter and wrong nullable

* Add RequeueQueue paramater to Webhook

* Better xml documentation

* Remove GatewayLimits class and other changes

- Remove GatewayLimits
- Transfer a few properties to DiscordSocketConfig
- Remove unnecessary usings

* Remove unnecessary using and wording

* Remove more unnecessary usings

* Change named Semaphores to SemaphoreSlim

* Remove unused using

* Update branch

* Fix merge conflicts and update to new ratelimit

* Fixing merge, ignore limit for heartbeat, and dispose

* Missed one place and better xml docs.

* Wait identify before opening the connection

* Only request identify ticket when needed

* Move identify control to sharded client

* Better description for IdentifyMaxConcurrency

* Add lock to InvalidSession

src/Discord.Net.WebSocket/DiscordSocketApiClient.cs

@@ -132,6 +132,8 @@ namespace Discord.API
             if (WebSocketClient == null)
                 throw new NotSupportedException("This client is not configured with WebSocket support.");
 
+            RequestQueue.ClearGatewayBuckets();
+
             //Re-create streams to reset the zlib state
             _compressed?.Dispose();
             _decompressor?.Dispose();
@@ -205,7 +207,11 @@ namespace Discord.API
             payload = new SocketFrame { Operation = (int)opCode, Payload = payload };
             if (payload != null)
                 bytes = Encoding.UTF8.GetBytes(SerializeJson(payload));
-            await RequestQueue.SendAsync(new WebSocketRequest(WebSocketClient, null, bytes, true, options)).ConfigureAwait(false);
+
+            options.IsGatewayBucket = true;
+            if (options.BucketId == null)
+                options.BucketId = GatewayBucket.Get(GatewayBucketType.Unbucketed).Id;
+            await RequestQueue.SendAsync(new WebSocketRequest(WebSocketClient, bytes, true, opCode == GatewayOpCode.Heartbeat, options)).ConfigureAwait(false);
             await _sentGatewayMessageEvent.InvokeAsync(opCode).ConfigureAwait(false);
         }
 
@@ -225,6 +231,8 @@ namespace Discord.API
             if (totalShards > 1)
                 msg.ShardingParams = new int[] { shardID, totalShards };
 
+            options.BucketId = GatewayBucket.Get(GatewayBucketType.Identify).Id;
+
             if (gatewayIntents.HasValue)
                 msg.Intents = (int)gatewayIntents.Value;
             else
@@ -258,6 +266,7 @@ namespace Discord.API
                 IsAFK = isAFK,
                 Game = game
             };
+            options.BucketId = GatewayBucket.Get(GatewayBucketType.PresenceUpdate).Id;
             await SendGatewayAsync(GatewayOpCode.StatusUpdate, args, options: options).ConfigureAwait(false);
         }
         public async Task SendRequestMembersAsync(IEnumerable<ulong> guildIds, RequestOptions options = null)