Only configure remove devtools security if Spring Security is enabled

Previously, RemoteDevToolsAutoConfiguration would try to configure
Spring Security if it was on the classpath. This led to a failure if
Spring Security was on the classpath but its auto-configuration was
disabled.

This commit updates the auto-configuration to be conditional on the
presence of Spring Security’s ObjectPostProcessor bean.

See gh-3889

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/RemoteDevToolsAutoConfiguration.java

@@ -25,6 +25,7 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
@@ -50,6 +51,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.annotation.Order;
 import org.springframework.http.server.ServerHttpRequest;
+import org.springframework.security.config.annotation.ObjectPostProcessor;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
 
@@ -158,6 +160,7 @@ public class RemoteDevToolsAutoConfiguration {
 
 	@Configuration
 	@ConditionalOnClass(WebSecurityConfigurerAdapter.class)
+	@ConditionalOnBean(ObjectPostProcessor.class)
 	static class RemoteDevToolsSecurityConfiguration {
 
 		@Bean