XD-2201 Fix LocalMessageBus Taps

JIRA: https://jira.spring.io/browse/XD-2201

When using a `LocalMessageBus`, if a tap throws
an exception, the message is not sent to the next
module in the stream.

- Set `ignoreFailures` on the wire tap's PubSub channel.
- Run taps on the local message bus's `executor`.
- Move fields in `MessageBusSupport` that are only used by `LocalMessageBus` to the `LocalMessageBus`.