Account for a missing rootcap

This way, it can be an empty list.

The first time the node starts there will be no rootcap and there cannot
easily be one unless the node is allowed to start so one can be created.

Fix handling of NativeStorageServer / actual storage server

My guess is most of  the time is spent in create_client_from_config and I
don't know if there's anything we can do about that.

Record pass spending during lease maintenance

It's not impossible or even disallowed.  However, if a storage index is
repeated it sure as heck better have the same object associated with it -
which this strategy does not ensure.

Fix `required_passes` docs and (implementation for large results)

The new direct positive-path Hypothesis-based test wants to pass in huge
numbers and the float-based implementation does not do well for these inputs.
Happily, we can do better.

Only the documentation was wrong, whew.

Add behavior to the client to automatically maintain leases

Add Python runtime requirements to setup.cfg