Describe source of parameters for ServerRequest (i.e. query string or
form data)

Prior to this commit, the TestGroup.CI enum constant was only used in a
single test method in spring-core. In order to enable that test, the
`testGroups` JVM system property was configured for the
Publication-master CI build plan; however, the `testGroups` system
property is not set when executing local builds. Consequently, there
has been a Gradle cache miss for every `test` task when building
something locally that's already been built on the CI server.

This commit addresses this issue by removing the `TestGroup.CI` enum
constant. The `-PtestGroups=ci` command line configuration for the
Publication-master CI build plan has also been removed on the CI server.

Closes gh-23918

* pr/23729:
  Fix spring-core jar task 'up-to-date'-ness

Closes gh-23729

See gh-23729

Closes gh-23788

Closes gh-23628

Closes gh-23841

See gh-23834

Closes gh-23882

See gh-23882

Closes gh-23880

This commit refactors several tests to use SocketUtils to find an
available port, compose a custom JMX service URL using that port, and
start an MBeanServer for the particular test using that port.

This commit also makes other changes to MBeanServer related tests in an
effort to make them more robust when executed concurrently.

Closes gh-23699

See gh-23884

Prior to this commit, the `DateFormatterRegistrar` would register the
annotation-based formatter before the pattern-based formatter. This
would create an issue when an application tries to convert a `String` to
an annotated `@DateTimeFormat Date`: since the converters are considered
in reversed order of registration in
`GenericConversionServicei#ConvertersForPair`, the pattern-based variant
would always be considered before the annotation-based variant,
overriding the developer's opinion.

This commit aligns the `DateFormatterRegistrar` with the
`DateTimeFormatterRegistrar` and registers the annotation-based variant
last.

Closes gh-23893

Closes gh-23832

Prior to this commit, if MockServletContext was configured with a
FileSystemResourceLoader, invocations of the following methods on a
Microsoft Windows operating system resulted in an InvalidPathException
if the supplied path contained a colon (such as "C:\\temp"). This is
inconsistent with the behavior on non-Windows operating systems. In
addition, for comparable errors resulting in an IOException, those
methods (except getRealPath()) return null instead of throwing the
exception.

- getResourcePaths()
- getResource()
- getResourceAsStream()
- getRealPath()

This commit makes handling of InvalidPathException and IOException
consistent for these methods: both exceptions now result in null be
returned by these methods.

Closes gh-23717

Previously, the infrastructure provided by WebMvcConfigurationSupport
and WebFluxConfigurationSupport can lead to unexpected results due to
the lack of qualifier for certain dependencies. Those configuration
classes refer to very specific beans, yet their injection points do not
define such qualifiers. As a result, if a candidate exists for the
requested type, the context will inject the existing bean and will
ignore a most specific one as such constraint it not defined. This can
be easily reproduced by having a primary Validator whereas a dedicated
"mvcValidator" is expected. Note that a parameter name is in no way a
constraint as the name is only used as a fallback when a single
candidate cannot be determined.

This commit provides explicit @Qualifier metadata for such injection
points, renaming the parameter name in the process to clarify that it
isn't relevant for the proper bean to be resolved by the context.

Closes gh-23887

Closes gh-23879

Closes gh-23834

Closes gh-23829

See gh-23741

A ResponseStatus exception now exposes extra method to return headers
for the response. This is used in ResponseStatusExceptionHandler to
apply the headers to the response.

Closes gh-23741

See gh-23793

Closes gh-23793

Closes gh-23794

Closes gh-23792

Latest dependency updates (Tomcat 9.0.27, Undertow 2.0.27, RxJava 2.2.13, Gson 2.8.6, Apache Johnzon 1.2.1, Hibernate ORM 5.4.8, EclipseLink 2.7.5, H2 1.4.200, POI 4.1.1, Quartz 2.3.2, WebJars Locator 0.42, HtmlUnit 2.36, Checkstyle 8.26, Mockito 3.1, Objenesis 3.1)