Add a reapAllVats method to the controller

[FUDCo]

Closes #8626

[warner]

Sounds good.. approved pending the suggested changes.

[warner]

Oh, neat, it didn't occur to me to use reapQueue for measuring this.. very clever.

Let's see, the kernel servicing code:

  function getNextMessageAndProcessor() {
    const acceptanceMessage = kernelKeeper.getNextAcceptanceQueueMsg();
    if (acceptanceMessage) {
      return {
        message: acceptanceMessage,
        processor: processAcceptanceMessage,
      };
    }
    const message =
      processGCActionSet(kernelKeeper) ||
      kernelKeeper.nextReapAction() ||
      kernelKeeper.getNextRunQueueMsg();
    return { message, processor: processDeliveryMessage };
  }

services the acceptanceQueue first (transferring items to the run-queue), then takes any GC action, then reapQueue, then finally runQueue. So when we use this feature for GC remediation, it's important to drain a controller.run() first (leaving all queues empty), then submit the c.reapAllVats(), then drain a second controller.run().

(if we submitted the reapAllVats() while there were still things in the acceptance or run queues, the reaps would happen first, then the real deliveries, which would leave GC stuff from the real deliveries still hanging out for an unknown period of time before the "organic" BOYDs finally happened)

[github-actions]

@FUDCo - This PR appears to be stuck. It's had a merge label for > 24 hours