DEV: Move core plugin TL -> group settings (#25355)

* DEV: Change poll_minimum_trust_level_to_create to group based setting

New setting is poll_create_allowed_groups

c.f. https://meta.discourse.org/t/changes-coming-to-settings-for-giving-access-to-features-from-trust-levels-to-groups/283408

* DEV: Move styleguide_admin_only to group based setting

Not exactly a TL -> group change, but still part of the
overall effort here:

https://meta.discourse.org/t/changes-coming-to-settings-for-giving-access-to-features-from-trust-levels-to-groups/283408

New setting is styleguide_allowed_groups

plugins/poll/db/post_migrate/20240122015626_fill_poll_create_allowed_groups_based_on_deprecated_setting.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+class FillPollCreateAllowedGroupsBasedOnDeprecatedSetting < ActiveRecord::Migration[7.0]
+  def up
+    old_setting_trust_level =
+      DB.query_single(
+        "SELECT value FROM site_settings WHERE name = 'poll_minimum_trust_level_to_create' LIMIT 1",
+      ).first
+
+    if old_setting_trust_level.present?
+      allowed_groups = "1#{old_setting_trust_level}"
+
+      DB.exec(
+        "INSERT INTO site_settings(name, value, data_type, created_at, updated_at)
+        VALUES('poll_create_allowed_groups', :setting, '20', NOW(), NOW())",
+        setting: allowed_groups,
+      )
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end