constructor({account} = {}) {
    super()
    this._account = account
    if (!this._account) {
      throw new Error("SyncTask requires an account")
    }
    this._logger = global.Logger.forAccount(this._account)
  }
SyncTask represents an operation run by the SyncWorker.
Any IMAP sync operation that runs during sync should extend from this class
and implement `runTask`

By default, this class ensures that we skip the operation if the message
processing queue is full, and ensures that the operation is interruptible by
extending from Interruptible.