Update `TestcontainersLifecycleBeanPostProcessor` so that containers
are now initialized either on the first `postProcessAfterInitialization`
call with a frozen configuration or just before a test container
property is supplied.
Prior to this commit, it was assumed that the first post-process call
after the configuration was frozen was suitably early to initialize
the containers. This turns out to not be no always the case.
Specifically, in the `finishBeanFactoryInitialization` method of
`AbstractApplicationContext` we see that `LoadTimeWeaverAware` beans
are obtained before the configuration is frozen. One such bean is
`DefaultPersistenceUnitManager` which is likely to need datasource
properties that will require a started container.
To fix the problem, the `TestcontainersPropertySource` now publishes
a `BeforeTestcontainersPropertySuppliedEvent` to the ApplicationContext
just before any value is supplied. By listening for this event, we can
ensure that containers are initialized and started before any dynamic
property is read.
Fixes gh-38913
Update `TestcontainersLifecycleBeanPostProcessor` so that containers
can actually be started in parallel.
Prior to this commit, `initializeStartables` would collect beans
and in the process trigger the `postProcessAfterInitialization` method
on each bean. This would see that `startablesInitialized` was `true`
and call `startableBean.start` directly. The result of this was that
beans were actually started sequentially and when the `start` method
was finally called it had nothing to do.
The updated code uses an enum rather than a boolean so that the
`postProcessAfterInitialization` method no longer attempts to start
beans unless `initializeStartables` has finished.
Fixes gh-38831
Update `TestcontainersLifecycleBeanPostProcessor` to restore early
container initialization logic and refine startup logic. Initial bean
access now again triggers the creation all container beans. In addition
the first access of a `Startable` bean now attempts to find and start
all other `Startable` beans.
Fixes gh-37989
Add support for a `spring.testcontainers.startup` property that can
be set to "sequential" or "parallel" to change how containers are
started.
Closes gh-37073
