Pass instance to _set_instance_error_state

This builds on commit 77a8478 so that _error_out_instance_on_exception
can pass the instance to _set_instance_error_state.  The next change in
the series will pass the instance down to _instance_update so if we have
an instance object we can avoid the direct call to conductor for state
changes and just update the instance object directly, which allows us to
remove instance.refresh() in the tests to pick up out-of-band database
updates on instance objects.

Part of blueprint compute-manager-objects-juno

Change-Id: I0a4607d368d3c226ca5a60d017d27c199c0dfe89
Avoid referencing stale instance/network_info dicts in firewall

This makes the virt.firewall code cleaner in terms of referencing
the cached instance and network_info code it stores. Before this
patch, concurrent instance operations could modify these two dicts
so that while we're iterating instances, the network_info dict
is suddenly missing information we need.

The right fix for this is to use instance objects and their
associated info_cache objects, but that's a larger fix and one
not as well-suited to backporting to previous releases which
suffer from this as well.

The approach taken here is that we store the instance and
network_info cache together in the same dict that we can pop()
from atomically (this is not really necessary, but helps to
prevent introducing more of these cases). When we iterate over
the contents, we iterate over a copy of the keys, being careful
not to let a suddenly-missing key break us, and passing the
details all the way down the stack instead of having deeper calls
hit the cache dicts again.

Change-Id: I33366f50024a82451842d045b830ab19b59879c3
Closes-bug: #1182131
Merge "Avoid referencing stale instance/network_info dicts in firewall"
Merge "Pass instance to _set_instance_error_state"