Attempt to reconnect on a gateway TimeoutError

[davfsa]

• Improve GatewayShard.is_alive detection
• Cleanup code for GatewayTransport.send_close

Checklist

• I have run nox and all the pipelines have passed.
• I have made unittests according to the code I have added/modified/deleted.

Related issues

Closes #1011

[FasterSpeeding]

Has this been live tested (like for a decent amount of time to catch normal cases, as well as against the case its trying to fix)?

[davfsa]

@HyperGH has been testing it for some days now and I have also mocked a bit to make it fail with a timeout error on that check specifically:

diff --git a/hikari/impl/shard.py b/hikari/impl/shard.py
index 036ca75e..89d08f5a 100644
--- a/hikari/impl/shard.py
+++ b/hikari/impl/shard.py
@@ -37,6 +37,7 @@ import zlib
 
 import aiohttp
 
+import hikari
 from hikari import _about as about
 from hikari import errors
 from hikari import intents as intents_
@@ -250,6 +251,8 @@ class _GatewayTransport(aiohttp.ClientWebSocketResponse):
 
         try:
             connector = net.create_tcp_connector(http_settings, dns_cache=False, limit=1)
+
+            http_settings = hikari.HTTPSettings(timeouts=hikari.HTTPTimeoutSettings(total=0.0000001))
             client_session = await exit_stack.enter_async_context(
                 net.create_client_session(connector, True, http_settings, True, proxy_settings.trust_env, cls)
             )