DEV: Switch over category settings to new table - Part 2 (#20580)

In #20135 we prevented invalid inputs from being accepted in category setting form fields on the front-end. We didn't do anything on the back-end at that time, because we were still discussing which path we wanted to take. Eventually we decided we want to move this to a new CategorySetting model.

This PR moves the num_auto_bump_daily from custom fields to the new CategorySetting model.

In addition it sets the default value to 0, which exhibits the same behaviour as when the value is NULL.

db/migrate/20230727015254_change_category_setting_num_auto_bump_daily_default.rb

@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+
+class ChangeCategorySettingNumAutoBumpDailyDefault < ActiveRecord::Migration[7.0]
+  def up
+    change_column_default :category_settings, :num_auto_bump_daily, 0
+
+    execute(<<~SQL)
+      WITH custom_fields AS (
+        SELECT
+          category_id,
+          MAX(
+            CASE WHEN (name = 'require_topic_approval')
+            THEN value ELSE NULL END
+          )::boolean AS require_topic_approval,
+          MAX(
+            CASE WHEN (name = 'require_reply_approval')
+            THEN value ELSE NULL END
+          )::boolean AS require_reply_approval,
+          MAX(
+            CASE WHEN (name = 'num_auto_bump_daily')
+            THEN value ELSE NULL END
+          )::integer AS num_auto_bump_daily,
+          NOW() AS created_at,
+          NOW() AS updated_at
+        FROM category_custom_fields
+        WHERE name IN (
+          'require_topic_approval',
+          'require_reply_approval',
+          'num_auto_bump_daily'
+        )
+        GROUP BY category_id
+      )
+      INSERT INTO
+        category_settings(
+          category_id,
+          require_topic_approval,
+          require_reply_approval,
+          num_auto_bump_daily,
+          created_at,
+          updated_at
+        )
+      SELECT * FROM custom_fields
+      ON CONFLICT (category_id) DO
+      UPDATE SET
+        require_topic_approval = EXCLUDED.require_topic_approval,
+        require_reply_approval = EXCLUDED.require_reply_approval,
+        num_auto_bump_daily = EXCLUDED.num_auto_bump_daily,
+        updated_at = NOW()
+    SQL
+
+    execute(<<~SQL)
+      UPDATE category_settings
+      SET num_auto_bump_daily = 0
+      WHERE num_auto_bump_daily IS NULL;
+    SQL
+  end
+
+  def down
+    change_column_default :category_settings, :num_auto_bump_daily, nil
+
+    execute(<<~SQL)
+      UPDATE category_settings
+      SET num_auto_bump_daily = NULL
+      WHERE num_auto_bump_daily = 0;
+    SQL
+  end
+end