fix queing key for start messages

[fixes #43512503]
Return droplet state over nats.

Listen to and respond to request `healthmanager.droplet` with a json
object containing all healthmanager data about the droplet.

The request message format is:

topic: healthmanager.droplet
payload: { "droplets" => [<droplet_id> , ... ] }

Intended for exploration/debugging.
bulk: credentials re-acquisition

Minor refactor, backfill specs

[Fixes #45413995]
bulk: batch_size default value, 50 -> 500
varz: add expected_stats_held?
bulk: fix: varz release on NATS timeout
add integration spec
spec: integration: Increase readability
remove framework and runtime
Merge pull request #2 from cloudfoundry/nuke-framework-runtime

remove framework and runtime
remove unnecessary namespacing
formatting
make sure that apps can be gc-ed if they were removed from ccdb
removed unnecessary &&
remove unnecessary namespacing
explicitness: stale -> expected_state_update_required
ignore unknown keys received from bulk api
stop instances of an extra app
formatting
make sure that app state becomes overdue when it was not updated with expected state