[JEP-228] Unforking XStream (#4944)

* Unforking XStream

* Some overrides missing from MapperDelegate

* [XSTR-762] writeReplace & readResolve must be accessible to be used from subclasses

* DomElement.click overloads changed incompatibly

* Giving up on ToolInstallation being Serializable.
Fixing MavenInstallation accordingly.
AntInstallation was already fixed: https://github.com/jenkinsci/ant-plugin/commit/c957dca4cd7789e3918e90ae020687aeaeea998e

* Relaxing message assertion in RobustReflectionConverter.randomExceptionsReported

* Picking up https://github.com/jenkinsci/matrix-auth-plugin/pull/89 caught via JobTest

* https://github.com/jenkinsci/jenkins-test-harness/pull/243 released

* Another case forgotten in 0e5aeec4ccc67207c0912ffe471fe5cf2815cf04

* XStream has SecurityMapper, but we have our own system already, so suppress warning

* GetMavenVersion was also serializing its outer class

* Trying to make ToolInstallation serializable compatible

* Avoid throwing IOException from PersistedList.inModified for common cases covered by https://github.com/jenkinsci/jenkins-test-harness/pull/243

* Found a way to avoid looking up XStream.converterRegistry by reflection

* XStream2Test.crashXstream now throwing ConversionException, not ForbiddenClassException

* Noting which version of the parent POM has https://github.com/jenkinsci/jenkins-test-harness/pull/243

* Refreshed Javadoc for XStream2

* The simplest solution to JENKINS-19561 seems to be to stop using autodetectAnnotations

* Fixing some deprecations in Robust*Converter

* Display OldDataMonitor errors from RobustReflectionConverter during functional tests

* Stray digit in test name

* Added XStream2AnnotationTest to clearly document incompatibility

* Picking up release of https://github.com/jenkinsci/matrix-auth-plugin/pull/89



Co-authored-by: Basil Crow <me@basilcrow.com>

Co-authored-by: Basil Crow <me@basilcrow.com>