DEV: Add rake task to bulk delete posts (#31576)

This PR adds a destroy:posts rake task that can be used to hard-delete a list of posts. Useful for dealing with large amounts of spam that has been soft deleted and needs to go.

Notes:

Works on both non-deleted and soft-deleted posts. (We might want to change this to work on only soft-deleted posts?)
Works exclusively on post IDs. We can't mix topic and post IDs as they might clash, and we have no way of resolving that ambiguity.
Accepts either a rake-style array of IDs or, more conveniently, you can pipe the argument in through STDIN.
Added a confirmation step since it's a fairly destructive operation.

lib/tasks/destroy.rake

@@ -50,3 +50,16 @@ task "destroy:categories" => :environment do |t, args|
   puts "Going to delete these categories: #{categories}"
   categories.each { |id| destroy_task.destroy_category(id, true) }
 end
+
+# Hard delete a list of posts by ID. Pass a comma
+# separated list either as a rake argument or through
+# STDIN, e.g. through a pipe.
+#
+#   Example: rake destroy:posts[4,8,15,16,23,42]
+#   Example: cat post_ids.txt | rake destroy:posts
+desc "Destroy a list of posts given by ID"
+task "destroy:posts" => :environment do |_task, args|
+  post_ids = args.extras.empty? ? STDIN.read.strip.split(",") : args.extras
+  puts "Going to delete these posts: #{post_ids}"
+  DestroyTask.new.destroy_posts(post_ids)
+end