Refactors the socket broadcast client

[arjo129]

This commit refactors the socket broadcast client. It switches out the underlying queue to a circular buffer, that way the memory pressure of the broadcast client remains constant without needing to do work at sporadic intervals. The new structure should hopefully also make it easier for someone to reason about the websocket layer and help us catch bugs if they exist.

I've also included an example socket client and a test server. The following plot shows memory usage after restarting the server multiple times:

[arjo129]

@aaronchongth, @koonpeng this is good to review again. I've added some integration tests.

[aaronchongth]

Just a few nitpicks from me, and I saw that some files were missing EOF new lines. But overall LGTM, we can wait for an approval from KP too

[koonpeng]

For this test, we can use a promise to wait until the reconnect happens before sending the 2nd message. Something like

const std::promise<void> on_init_promise;

auto init_function(std::promise<void>& promise) {
  ...
  promise.set_value();
}

REQUIRE_NO_THROW(on_init_promise.get_future().wait_for(1s));

// send 2nd message

Technically we can use this for test_client.cpp as well, but this requires the use of the reconnect init function, which kind of makes the 2 tests overlap.

[arjo129]

After much hammering... I'm sorry to say there still are corner cases... It seems that sometimes on my machine the reconnection does not guarantee it stays... reconnected. Im trying to figure out if its abug in the logic or something else.

[koonpeng]

There is a minor style issue which is making the non-asan test failing.