Fix WebSecurityCustomizer beans are excluded by WebMvcTest.

[LumanSuen]

See gh-47255

Added org.springframework.security.config.annotation.web.configuration.WebSecurityCustomizer as an optional include to enable the loading of the following configurations.

@Configuration
public class WebSecurityCustomizersConfiguration implements WebSecurityCustomizer {
    public void customize(WebSecurity web){
        web.ignoring().requestMatchers("/favicon.ico");
    }
}

However, please note that loading of @Bean definitions is still not supported.

@Configuration
public class WebSecurityCustomizersConfiguration implements WebSecurityCustomizer {
   @Bean
    public WebSecurityCustomizer faviconSecurityCustomizer() {
        return (web) -> web.ignoring().requestMatchers("/favicon.ico");
    }
}

Because @Configuration classes are not loaded by @WebMvcTest, I also can’t directly add Configuration.class to the includes, as that would make the change too extensive.

Therefore, I added org.springframework.security.config.annotation.web.configuration.WebSecurityCustomizer in the same way as org.springframework.security.web.SecurityFilterChain.

[wilkinsona]

Thanks for the PR, @LumanSuen, but this wasn't the right approach following the modularization in 4.0.