Adds auto-config for Spring for Apache Pulsar transactions.
Introduces a new `spring.pulsar.transaction.enabled` property
which can be used to enable transactions. This feature is
opt-in and remains disabled by default.
See gh-40189
Co-authored-by: Andy Wilkinson <andy.wilkinson@broadcom.com>
Co-authored-by: Phillip Webb <phil.webb@broadcom.com>