Do not allow connection output buffer to exceed configured limit (#196)

### Public-Facing Changes
- Do not allow connection output buffer to exceed configured limit

### Description
Makes sure that we only put messages in the output buffer if they do not
cause the output buffer to exceed the user configured limit.

This mitigates that larger messages (images / pointclouds, ...) prevent
smaller messages from being sent (see #174)

foxglove_bridge_base/include/foxglove_bridge/websocket_server.hpp

@@ -1056,7 +1056,7 @@ inline void Server<ServerConfiguration>::sendMessage(ConnHandle clientHandle, Ch
   }
 
   const auto bufferSizeinBytes = con->get_buffered_amount();
-  if (bufferSizeinBytes >= _options.sendBufferLimitBytes) {
+  if (bufferSizeinBytes + payloadSize >= _options.sendBufferLimitBytes) {
     FOXGLOVE_DEBOUNCE(
       [this]() {
         _server.get_elog().write(