[3.1 -> main] Fix crash on startup if port already in use

[heifner]

Do not throw exception in posted lambdas to main thread as this causes non-joined threads to terminate. Instead report error and quit the application.

error 2022-08-30T13:15:52.885 nodeos    net_plugin.cpp:3747           operator()           ] net_plugin::plugin_startup failed to bind to port 9876, bind: Address already in use
info  2022-08-30T13:15:52.885 nodeos    resource_monitor_plugi:122    plugin_shutdown      ] shutdown...
info  2022-08-30T13:15:52.885 nodeos    resource_monitor_plugi:129    plugin_shutdown      ] exit shutdown
info  2022-08-30T13:15:52.885 nodeos    net_plugin.cpp:3776           plugin_shutdown      ] shutdown..
info  2022-08-30T13:15:52.885 nodeos    net_plugin.cpp:3793           plugin_shutdown      ] close 0 connections
info  2022-08-30T13:15:52.885 nodeos    net_plugin.cpp:3813           plugin_shutdown      ] exit shutdown
info  2022-08-30T13:15:52.887 nodeos    main.cpp:181                  main                 ] nodeos successfully exiting

Resolves #60