See gh-12602

Since Servlet.fn support has been added in Spring Framework, new
infrastructure beans (like `HandlerAdapter` and `HandlerMapping`) have
been added.

This commit adapts the Spring MVC auto-configuration tests to reflect
those changes.

Closes gh-16272

For webflux, security configuration is configured via a bean of type
`SecurityWebFilterChain` and not `ServerHttpSecurity`. We would have changed
the include to be `SecurityWebFilterChain` but the filter only applies to
beans registered via component scanning and not those registered in
`@Configuration` classes, making the includes redundant.

See gh-16088

Closes gh-16274

See gh-16270

Closes gh-15813

Closes gh-16272

Closes gh-16273

* gh-16270:
  Use HTTPS for external links in XML files

See gh-16270

* pr/16269:
  Use the latest DTD declaration for Checkstyle

Closes gh-16269

* pr/16265:
  Remove explicit types

Closes gh-16265

Closes gh-16033

Closes gh-16229

* gh-16247:
  Update build and setup configuration to use HTTPS

Closes gh-16247

See gh-16247