Deploy across an entire web cluster

Adds deploy, undeploy, and redeployAll to webapp cluster entities (DWAC and ControlledDWAC).

Also fixes some issues noticed in how tasks are tracked and displayed.
From the method name, I didn't guess that the error would not `throwsErrorOnAccess`. Perhaps `newInstanceWithInformativeWarning` would be better (but that doesn't fit nicely with `getError`)?