* pr/16478:
  Fix Thymeleaf deprecations

Closes gh-16478

* pr/16476:
  Fix compilation error

Closes gh-16476

Fixes gh-16184

This commit also adds tests to ensure that the child
management context works when lazy initialization is
enabled. Also, it adds a BeanFactoryPostProcessor to
the child context so that the server is created and
listening for requests but other beans in the child
context are not created until requested.

See gh-16184

Closes gh-16473

Closes gh-15378

Users calling the methods will still face problems but at least they
will have some guidance.

Closes gh-16096

This commit migrates `AnnotationConfigReactiveWebApplicationContext`
parent to the `GenericApplicationContext` abstraction. Any use of
`AnnotationConfigWebApplicationContext` is also removed as it also
inherits from the `AbstractRefreshableApplicationContext` outdated
hierarchy.

A new `AnnotationConfigServletWebApplicationContext` context is
introduced instead, extending from `GenericApplicationContext` and
providing the counter part of the reactive context for the Servlet-based
web app tests.

See gh-16096

* pr/16446:
  Polish "Polish embedded tomcat setup"
  Polish embedded tomcat setup

Closes gh-16446

See gh-16446

* pr/16342:
  Polish "Simplify the configuration of the ProtocolHandler"
  Simplify the configuration of the ProtocolHandler

Closes gh-16342

This commit introduces a new callback interface that can
be used to customize the ProtocolHandler on a Tomcat Connector.

See gh-16342

See gh-16458

Closes gh-16451

This commit improves type resolution for a unresolved generic type that
uses itself in its upper bound declaration.

Closes gh-16451

Closes gh-16461

Closes gh-16442

Closes gh-16460

Closes gh-16458

Closes gh-16172

Fixes gh-16453