refactor(gossip): improved init flow

[0xNineteen]

• Moved GossipService allocation to heap with new create() function
  • there were a random number of structs which were heap allocated, whereas others were not - this change puts everything on the stack, and uses the create method to make everything on the heap (which it should be due to the multi-threaded nature of gossip)
• Removed thread pool dependency from GossipTable initialization (was dead code)
• Removed unused echo server implementation (was dead code)
  • ticket to add it back with working server here
• Added proper cleanup of muxes in GossipService deinit

[0xNineteen]

• refactor(gossip): move service_manager inside the GossipService struct #410
• refactor(gossip): improved init flow #407 👈 (View in Graphite)
• main

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[yewman]

Love these changes, just a couple of comments that I am interested to hear your view on

[yewman]

lgtm