channel should notify upstream about revoked token

[petri]

The topic v2.system.token_revoked.{id} is implicitly subscribed by all channels. Details in https://developer.genesys.cloud/api/rest/v2/notifications/available_topics .

Suggest e.g. ChannelTokenRevoked(ChannelException).

Message schema:

{
  "channelId": "string",
  "systemTopicType": {
    "enum": "no_longer_subscribed|subscription_changed|token_revoked"
  },
  "correlationId": "string",
  "organizationId": "string",
  "userId": "string",
  "oauthClientId": "string",
  "reason": {
    "enum": "another_channel_subscribed|user_tokens_revoked"
  },
  "message": "string",
  "data": "object"
}```