Closes gh-7107

Closes gh-10819

See gh-10817

This commit updates `WebFluxSecurityConfiguration` to look for a
`WebFilterChainProxy` rather than the default configuration that
`@EnableWebFluxSecurity` triggers. The latter is now package private.

* pr/10805:
  Remove unnecessary assignments

Closes gh-10805

* pr/10806:
  Handle null early in Sanitizer.sanitize()

Closes gh-10806

* pr/10810:
  Fix typos in AutoConfigureRestDocs

Closes gh-10810

* gh-10764:
  Wrap using-spring-boot.adoc at 90 characters
  Editorial changes to Using Spring Boot documentation

Closes gh-10765

See gh-10765

* gh-10763:
  Wrap getting-started.adoc at 90 characters
  Editorial changes to Getting Started documentation

Closes gh-10763

See gh-10763

See gh-10754

Closes gh-10758

* pr/10612:
  Polish JobLauncherCommandLineRunner

The JobLauncherCommandLineRunner reassigned method arguments inside the
merge method. Instead of reassigning the method argument just return
the new instance directly.

Also some minor cleanup (unnesseccary null check and continue keyword).

Closes gh-10612

* pr/10774:
  Remove static Boot version from documentation

Closes gh-10774

See gh-10511

Previously, ConfigurationPropertiesBindingPostProcessor had a number
of setter methods that implied that its configuration was more mutable
than it actually is and would only have an effect when called early
on in the post-processor's lifecycle.

This commit clarifies how the post-processor can be configured by
removing the misleading setters.

Closes gh-10598

Previously, configuration properties binding would only see changes to
the environment if there was no PropertySourcesPlaceholderConfigurer
in the context. This happened because
PropertySourcesPlaceholderConfigurer wrapped the Environment in a
PropertySource, effectively hiding it from the change tracking
performed by SpringConfigurationPropertySources.

This commit updates ConfigurationPropertiesBindingPostProcessor so
that it ignores the environment property source contained by
PropertySourcesPlaceholderConfigurer and uses a composite of
the PropertySourcesPlaceholderConfigurer's other property sources and
the Environment's PropertySources instead.

See gh-10769

Closes gh-10759

Closes gh-10796

See gh-10758

Closes gh-10135

Closes gh-10792

* pr/10511:
  Polish "Add runApplication() Kotlin top level function"
  Specify kotlin-maven-plugin version for plugin management
  Add runApplication() Kotlin top level function
  Add Kotlin main artifacts to dependency management