Issue: SPR-16987

Issue: SPR-13188

In particular, avoid accidental usage of ASM for core JDK types - which will fail in case of a new bytecode version in the JDK, even if the application itself has been compiled with an earlier bytecode target.

Issue: SPR-10292

Prior to this commit many test utility classes and sample beans were
duplicated across projects. This was previously necessary due to the
fact that dependent test sources were not shared during a gradle
build. Since the introduction of the 'test-source-set-dependencies'
gradle plugin this is no longer the case.

This commit attempts to remove as much duplicate code as possible,
co-locating test utilities and beans in the most suitable project.
For example, test beans are now located in the 'spring-beans'
project.

Some of the duplicated code had started to drift apart when
modifications made in one project where not ported to others. All
changes have now been consolidated and when necessary existing tests
have been refactored to account for the differences.

Conflicts:
	spring-beans/src/test/java/org/springframework/beans/factory/ConcurrentBeanFactoryTests.java
	spring-beans/src/test/java/org/springframework/beans/factory/support/BeanFactoryGenericsTests.java
	spring-beans/src/test/java/org/springframework/beans/support/PagedListHolderTests.java

Issue: SPR-10129

This commit eliminates the 'integration-tests' subproject in favor of
managing these sources under the root project's own 'src' directory.

This helps to avoid special-case handling for integration-tests in the
Gradle build, e.g. avoiding publication of jars to Artifactory /
Maven Central.

It is also semantically more correct. This is not a Spring Framework
subproject so much as it is a collection of integration tests that
span functionality across many subprojects. In this way, it makes
sense to place them directly under the root project.

Issue: SPR-8116