FEATURE: Add events when web and sidekiq forks start

config/unicorn.conf.rb

@@ -114,6 +114,8 @@ before_fork do |server, worker|
 
       require 'demon/sidekiq'
 
+      DiscourseEvent.trigger(:sidekiq_fork_started)
+
       if @stats_socket_dir
         Demon::Sidekiq.after_fork do
           start_stats_socket(server)
@@ -218,6 +220,8 @@ end
 after_fork do |server, worker|
   start_stats_socket(server)
 
+  DiscourseEvent.trigger(:web_fork_started)
+
   # warm up v8 after fork, that way we do not fork a v8 context
   # it may cause issues if bg threads in a v8 isolate randomly stop
   # working due to fork