Blocked on #476 due to the need for process-boundary crossing in kernel-test

Properly threading the logging in case of testing can be done in a few ways:

• use a test vat bundler which endows the vat with our special console service
• have the vat supervisor endow the vat with the console and rewrite the vat to expect it as a power

But in either case the test must cross the process boundary (write from a child process, read from the parent). We have already solved this problem with streams; the thing is just to have the VatHandle expose the read end of the console in a usable way.

Stale