Release 0.8.4

What's Changed

• Route STOMP traffic by destination group by @yungwangoh in #138
• Isolate destination groups and speed up trie routing by @yungwangoh in #141
• Add destination group support to Titan clients by @yungwangoh in #142
• Support queue groups in management and CLI and fix lifecycle races by @yungwangoh in #143
• Add stability measurement tooling and baseline runs for 0.9.0 by @yungwangoh in #144
• Stabilize STOMP sessions by @yungwangoh in #145
• Apply the Titan flow identity to project icons and README by @yungwangoh in #146
• Return completion stages from dispatch exporters by @yungwangoh in #147
• Interrupt fanout consumers on cancellation by @yungwangoh in #148
• Propagate channel writability events by @yungwangoh in #149
• Avoid recreating deleted queues during consumer startup by @yungwangoh in #150
• Move queue deletion into the dispatch gateway by @yungwangoh in #151
• Keep queue capacity reserved until export completes by @yungwangoh in #152
• Complete dispatch exports at the handoff boundary by @yungwangoh in #154
• Update documentation for 0.8.4 by @yungwangoh in #155

Full Changelog: 0.8.3...0.8.4