Enable deprecated/removed Mutation Events (obsolete)

OBSOLETE: This policy is obsolete and doesn't work after Microsoft Edge 136. This policy provides a temporary opt-in back to a deprecated and removed set of platform events named Mutation Events. If you enable this policy, mutation events continue to be fired, even if they've been disabled by default for normal web users. If you disable or don't configure this policy, these events won't be fired. Note: This policy is a temporary workaround and will be obsolete starting with Microsoft Edge version 137.