DEV: Autoload and segregate features to prep for migration (#341)

This commit autoloads plugin files, and also extracts features into their own modules.
- `plugin.rb` is smaller
- external plugins like discourse-automation and discourse-assign have their own entrypoints
- solved filters as well

lib/discourse_dev/discourse_solved.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+module DiscourseDev
+  class DiscourseSolved
+    def self.populate(plugin)
+      plugin.on(:after_populate_dev_records) do |records, type|
+        next unless SiteSetting.solved_enabled
+
+        if type == :category
+          next if SiteSetting.allow_solved_on_all_topics
+
+          solved_category =
+            DiscourseDev::Record.random(
+              Category.where(
+                read_restricted: false,
+                id: records.pluck(:id),
+                parent_category_id: nil,
+              ),
+            )
+          CategoryCustomField.create!(
+            category_id: solved_category.id,
+            name: ::DiscourseSolved::ENABLE_ACCEPTED_ANSWERS_CUSTOM_FIELD,
+            value: "true",
+          )
+          puts "discourse-solved enabled on category '#{solved_category.name}' (#{solved_category.id})."
+        elsif type == :topic
+          topics = Topic.where(id: records.pluck(:id))
+
+          unless SiteSetting.allow_solved_on_all_topics
+            solved_category_id =
+              CategoryCustomField
+                .where(name: ::DiscourseSolved::ENABLE_ACCEPTED_ANSWERS_CUSTOM_FIELD, value: "true")
+                .first
+                .category_id
+
+            unless topics.exists?(category_id: solved_category_id)
+              topics.last.update(category_id: solved_category_id)
+            end
+
+            topics = topics.where(category_id: solved_category_id)
+          end
+
+          solved_topic = DiscourseDev::Record.random(topics)
+          post = nil
+
+          if solved_topic.posts_count > 1
+            post = DiscourseDev::Record.random(solved_topic.posts.where.not(post_number: 1))
+          else
+            post = DiscourseDev::Post.new(solved_topic, 1).create!
+          end
+
+          ::DiscourseSolved.accept_answer!(post, post.topic.user, topic: post.topic)
+        end
+      end
+    end
+  end
+end