See gh-27086

See gh-27086

Closes gh-27086

Closes gh-27082

Closes gh-27081

Closes gh-27080

Previously, SpringApplicationShutdownHook would call close() on any
registered application context even if it wasn't active as it had
already been closed. This could lead to deadlock if the context was
closed and System.exit was called during application context refresh.

This commit updates SpringApplicationShutdownHook so that it only
calls close() on active contexts. This prevents deadlock as it avoids
trying to sychronize on the context's startupShutdownMonitor on
the shutdown hook thread while it's still held on the main thread
which called System.exit and is waiting for all of the shutdown hooks
to complete.

Fixes gh-27049

See gh-27046

See gh-27045

See gh-27044

See gh-27072

See gh-27043

Update calls to `Instantiator` to that they also include
`ResourceLoader.getClassLoader()`.

Closes gh-27071

Fixes gh-27072

Update `Instantiator` so that it can accept a `ClassLoader` when
creating instances and rework `EnvironmentPostProcessorsFactory` to
use the new methods.

Prior to this commit we would use the `ClassLoader` to get the class
names from `SpringFactories` but not when actually creating the
instances.

Fixes gh-27043

See gh-26978

Closes gh-27070

Closes gh-27069

Closes gh-27068

Closes gh-27067

Closes gh-27066

Closes gh-26978

Closes gh-26974

Closes gh-26973

Closes gh-26972

Closes gh-26967

Closes gh-26966

* pr/26930:
  Avoid illegal reflective access in CLI tests

Closes gh-26930

See gh-26930

Closes gh-27062

Closes gh-27026