fix: Allow users with report_manage permission to access CSAT reports (#11625)

- Extended CsatSurveyResponsePolicy to support report_manage permission
- Added enterprise extension module following existing pattern
- Users with report_manage custom role can now access CSAT index,
metrics, and download
- Added comprehensive tests for both base and enterprise policy behavior

enterprise/app/policies/enterprise/csat_survey_response_policy.rb

@@ -0,0 +1,13 @@
+module Enterprise::CsatSurveyResponsePolicy
+  def index?
+    @account_user.custom_role&.permissions&.include?('report_manage') || super
+  end
+
+  def metrics?
+    @account_user.custom_role&.permissions&.include?('report_manage') || super
+  end
+
+  def download?
+    @account_user.custom_role&.permissions&.include?('report_manage') || super
+  end
+end