This commit moves the `spring.pid.*` metadata to the relevant project. It
also updates the doc to refer to the new `ApplicationPidFileWriter`
rather than the one in its deprecatred form.

Closes gh-8196

See gh-8196

Previously, TestRestTemplate applied the root URI to URIs by
converting them to a String and then passing the String to the
RestTemplate delegate. Being a String, meant that the URI passed
through RestTemplate's standard URI template expansion processing
using the configured UriTemplateHandler. While this caused the root
URI to be applied, it also had the unwanted side-effect of
encoding the URI for a second time.

This commit updates TestRestTemplate so that, when configured with a
RootUriTemplateHandler, it applies the root URI directly and then
passes a modified URI to the RestTemplate delegate. Being a URI means
that no template expansion is performed and the possible double
encoding is avoided.

Closes gh-8163

* pr/8157:
  Polish contribution
  Update copyright header

Closes gh-8157

See gh-8157

Previously, ManagementContextConfiguration classes were loaded to
allow them to be ordered based on either @Order or implementing
Ordered. This had the unwanted side-effect of possibly logging
unwanted INFO messages if the reflection-based annotation
introspection failed. One cause of this was @ConditionalOnClass when
the referenced class was not on the classpath.

This commit uses the ASM-based annotation metadata reading to
determine the order of a management context configuration class based
on the @Order annotation. The classes are then sorted using a standard
OrderComparator. Note that Ordering via implemented Ordered is not
supported as it cannot be determine without loading the class.

Closes gh-8112

See gh-8112

Closes gh-8032

Closes gh-7703

Update all `EmbeddedServletContainer` implementations to ensure that
the `start()` method can be called multiple times, with the second call
being ignored.

Fixes gh-8036

Update `Log4J2LoggingSystem` and `LogbackLoggingSystem` to ensure
that filters are removed when the `cleanUp` method is called. Prior
to this commit application failures would not remove the filter and
no log messages would appear.

The `LoggingApplicationListener` has also been updated since it
previously failed to handle `ApplicationFailureEvents`.

Finally `EventPublishingRunListener` and `DelegatingApplicationListener`
have been updated to deal with `null` parameters and to cope with
listener errors.

Fixes gh-7758

This reverts commit 70cd5c42.

See gh-8083

Closes gh-7774

Previously, AbstractEmbeddedServletContainerFactory detected an
exploded war by looking for `/WEB-INF/` in the path of its code
source's location. This failed on Windows due to the use of `\` rather
than `/` separators.

This commit updates AbstractEmbeddedServletContainerFactory to
uses the OS's separator rather than hardcoding `/`.

Closes gh-8100

Closes gh-8102

Closes gh-8086

Closes gh-8085

Closes gh-8084

Closes gh-8083

Closes gh-8082

Closes gh-8081

Closes gh-8080

Closes gh-8079

Closes gh-8078

Closes gh-69

See gh-7774

Closes gh-7652

* pr/8057:
  Fix entry in broken-initialization.factories

Closes gh-8057

Closes gh-7360

Closes gh-2753

* pr/8039:
  Indenting SpringApplication javadoc code

Closes gh-8039

Closes gh-8040

Closes gh-8033