DEV: add debugging scripts for memory leaks

These scripts are somewhat rough but I needed them to help debug a memory
leak we have noticed in rails 6.

The biggest object script finds all the biggest objects we have in memory
after boot.

The test memory leak runs a very simple iteration through all multisites
and observed memory.

script/biggest_objects.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+# simple script to measure largest objects in memory post boot
+
+if ENV['RAILS_ENV'] != "production"
+  exec "RAILS_ENV=production ruby #{__FILE__}"
+end
+
+require 'objspace'
+
+ObjectSpace.trace_object_allocations do
+
+  require File.expand_path("../../config/environment", __FILE__)
+
+  Rails.application.routes.recognize_path('abc') rescue nil
+
+  # load up the yaml for the localization bits, in master process
+  I18n.t(:posts)
+
+  RailsMultisite::ConnectionManagement.each_connection do
+    (ActiveRecord::Base.connection.tables - %w[schema_migrations versions]).each do |table|
+      table.classify.constantize.first rescue nil
+    end
+  end
+
+end
+
+5.times do
+  GC.start(full_mark: true, immediate_sweep: true)
+end
+
+[String, Array, Hash].each do |klass|
+  ObjectSpace.each_object(klass).sort { |a, b| b.length <=> a.length }.first(50).each do |obj|
+    puts "#{klass} size: #{obj.length} #{ObjectSpace.allocation_sourcefile(obj)} #{ObjectSpace.allocation_sourceline(obj)}"
+  end
+end