Restructure web auto-configuration

Restructure `org.springframework.boot.autoconfigure.web` to better align
with the new package structure in `spring-boot`.

Auto-configuration is now split into client, servlet and reactive
sub-packages. In addition a new `http` package now handles common
HTTP concerns.

Fixes gh-8616

spring-boot-test/src/test/java/org/springframework/boot/test/context/AbstractSpringBootTestWebServerWebEnvironmentTests.java

@@ -16,8 +16,13 @@
 
 package org.springframework.boot.test.context;
 
+import java.net.URL;
+
 import javax.servlet.ServletContext;
 
+import org.apache.catalina.webresources.TomcatURLStreamHandlerFactory;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
 import org.junit.Test;
 
 import org.springframework.beans.factory.annotation.Autowired;
@@ -28,6 +33,7 @@ import org.springframework.boot.web.server.LocalServerPort;
 import org.springframework.boot.web.servlet.server.ServletWebServerFactory;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
+import org.springframework.test.util.ReflectionTestUtils;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.context.WebApplicationContext;
@@ -59,6 +65,14 @@ public abstract class AbstractSpringBootTestWebServerWebEnvironmentTests {
 	@Autowired
 	private TestRestTemplate restTemplate;
 
+	@BeforeClass
+	@AfterClass
+	public static void uninstallUrlStreamHandlerFactory() {
+		ReflectionTestUtils.setField(TomcatURLStreamHandlerFactory.class, "instance",
+				null);
+		ReflectionTestUtils.setField(URL.class, "factory", null);
+	}
+
 	public WebApplicationContext getContext() {
 		return this.context;
 	}