DEV: Reintroduce chat rake dev generate tasks (#21164)

This is to help generate random channels and chat
messages for local dev. This was removed in 12a18d4d553b6c11a7f45f686ab699aa72c3312f
presumably because it was not worth refactoring at the
time.

I've only added these tasks:

- `rake chat:message:populate\[113,20\]` (channel_id, count)
  - Generates the count of messages for a channel ID provided,
    otherwise uses a random channel and 200 count.
- `rake chat:category_channel:populate`
  - Creates a chat channel for a random category.
- `rake chat🧵populate\[132,5\]` (channel_id, message_count)
  - Creates a thread with N messages in the specified channel,
    and enables threading in that channel if necessary

lib/discourse_dev/record.rb

@@ -37,7 +37,7 @@ module DiscourseDev
         raise 'To run this rake task in a production site, set the value of `ALLOW_DEV_POPULATE` environment variable to "1"'
       end
 
-      unless ignore_current_count
+      unless ignore_current_count || @ignore_current_count
         if current_count >= @count
           puts "Already have #{current_count} #{type} records"
 
@@ -68,8 +68,8 @@ module DiscourseDev
       model.count
     end
 
-    def self.populate!(*args)
-      self.new(*args).populate!
+    def self.populate!(**args)
+      self.new(**args).populate!
     end
 
     def self.random(model, use_existing_records: true)