Merge branch 'dev-caching' into 'master'

Support caching in development environment

See merge request gitlab-org/gitlab!54103

config/environments/development.rb

@@ -11,7 +11,13 @@ Rails.application.configure do
   # Show full error reports and disable caching
   config.active_record.verbose_query_logs  = true
   config.consider_all_requests_local       = true
-  config.action_controller.perform_caching = false
+
+  if Rails.root.join('tmp', 'caching-dev.txt').exist?
+    config.action_controller.perform_caching = true
+    config.action_controller.enable_fragment_cache_logging = true
+  else
+    config.action_controller.perform_caching = false
+  end
 
   # Show a warning when a large data set is loaded into memory
   config.active_record.warn_on_records_fetched_greater_than = 1000