Break down Core and Web chapters in reference doc

Core and Web chapters are important chapters in the Spring Framework
reference documentation, and splitting them in multiple files will
help to evolve the documentation while not creating too many files.

Issue: SPR-12309

src/asciidoc/testing.adoc

@@ -386,11 +386,11 @@ loader since the default loader supports either resource `locations` or annotate
 +
 
 [NOTE]
-===
+====
 `@ContextConfiguration` provides support for __inheriting__ resource locations or
 configuration classes as well as context initializers declared by superclasses by
 default.
-===
+====
 
 +
 
@@ -530,13 +530,13 @@ should be active when loading an `ApplicationContext` for test classes.
 +
 
 [NOTE]
-===
+====
 `@ActiveProfiles` provides support for __inheriting__ active bean definition profiles
 declared by superclasses by default. It is also possible to resolve active bean
 definition profiles programmatically by implementing a custom
 <<testcontext-ctx-management-env-profiles-ActiveProfilesResolver,`ActiveProfilesResolver`>>
 and registering it via the `resolver` attribute of `@ActiveProfiles`.
-===
+====
 
 +
 
@@ -757,7 +757,7 @@ conjunction with `@ContextConfiguration`.
 +
 
 [NOTE]
-===
+====
 If the default conventions are sufficient for your test configuration, you can avoid
 using `@TransactionConfiguration` altogether. In other words, if you have only one
 transaction manager -- or if you have multiple transaction managers but the transaction
@@ -765,7 +765,7 @@ manager for tests is named "transactionManager" or specified via a
 `TransactionManagementConfigurer` -- and if you want transactions to roll back
 automatically, then there is no need to annotate your test class with
 `@TransactionConfiguration`.
-===
+====
 
 +
 
@@ -916,7 +916,7 @@ tests and can be used anywhere in the Spring Framework.
 
 .JSR-250 Lifecycle Annotations
 [NOTE]
-===
+====
 In the Spring TestContext Framework `@PostConstruct` and `@PreDestroy` may be used with
 standard semantics on any application components configured in the `ApplicationContext`;
 however, these lifecycle annotations have limited usage within an actual test class.
@@ -928,7 +928,7 @@ class. On the other hand, if a method within a test class is annotated with
 `@PreDestroy`, that method will __never__ be executed. Within a test class it is
 therefore recommended to use test lifecycle callbacks from the underlying test framework
 instead of `@PostConstruct` and `@PreDestroy`.
-===
+====
 
 
 [[integration-testing-annotations-junit]]
@@ -1819,11 +1819,11 @@ annotation and supplying a list of profiles that should be activated when loadin
 `ApplicationContext` for the test.
 
 [NOTE]
-===
+====
 `@ActiveProfiles` may be used with any implementation of the new `SmartContextLoader`
 SPI, but `@ActiveProfiles` is not supported with implementations of the older
 `ContextLoader` SPI.
-===
+====
 
 Let's take a look at some examples with XML configuration and `@Configuration` classes.
 
@@ -2149,7 +2149,7 @@ the `Environment`'s set of `PropertySources` for the `ApplicationContext` loaded
 annotated integration test.
 
 [NOTE]
-===
+====
 `@TestPropertySource` may be used with any implementation of the `SmartContextLoader`
 SPI, but `@TestPropertySource` is not supported with implementations of the older
 `ContextLoader` SPI.
@@ -2157,7 +2157,7 @@ SPI, but `@TestPropertySource` is not supported with implementations of the olde
 Implementations of `SmartContextLoader` gain access to merged test property source values
 via the `getPropertySourceLocations()` and `getPropertySourceProperties()` methods in
 `MergedContextConfiguration`.
-===
+====
 
 *Declaring test property sources*
 
@@ -2494,7 +2494,7 @@ is much faster.
 
 .Test suites and forked processes
 [NOTE]
-===
+====
 The Spring TestContext framework stores application contexts in a __static__ cache. This
 means that the context is literally stored in a `static` variable. In other words, if
 tests execute in separate processes the static cache will be cleared between each test
@@ -2509,7 +2509,7 @@ http://maven.apache.org/plugins/maven-surefire-plugin/test-mojo.html#forkMode[fo
 for the Maven Surefire plug-in is set to `always` or `pertest`, the TestContext
 framework will not be able to cache application contexts between test classes and the
 build process will run significantly slower as a result.
-===
+====
 
 Since having a large number of application contexts loaded within a given test suite can
 cause the suite to take an unnecessarily long time to execute, it is often beneficial to
@@ -2678,13 +2678,13 @@ application context for `ExtendedTests` will be loaded only from
 
 .Dirtying a context within a context hierarchy
 [NOTE]
-===
+====
 If `@DirtiesContext` is used in a test whose context is configured as part of a context
 hierarchy, the `hierarchyMode` flag can be used to control how the context cache is
 cleared. For further details consult the discussion of `@DirtiesContext` in
 <<integration-testing-annotations-spring,Spring Testing Annotations>> and the
 `@DirtiesContext` javadocs.
-===
+====
 --
 
 
@@ -2726,7 +2726,7 @@ use of `@Autowired` on fields and setter methods. The application context config
 is presented after all sample code listings.
 
 [NOTE]
-===
+====
 The dependency injection behavior in the following code listings is not specific to
 JUnit. The same DI techniques can be used in conjunction with any testing framework.
 
@@ -2734,7 +2734,7 @@ The following examples make calls to static assertion methods such as `assertNot
 but without prepending the call with `Assert`. In such cases, assume that the method was
 properly imported through an `import static` declaration that is not shown in the
 example.
-===
+====
 
 The first code listing shows a JUnit-based implementation of the test class that uses
 `@Autowired` for field injection.