Implement `Drop` for `Runtime` (#848)
Implement `Drop` for `Runtime` (#848)

This just forwards to `Runtime::stop`, but it ensures that the
appropriate cleanup is performed when `Runtime` gets out of scope, which
should make it more likely that we would catch any issues in tests.
project-oak/oak,project-oak/oak,project-oak/oak,project-oak/oak,project-oak/oak,project-oak/oak,project-oak/oak