Migrate ApplicationContext to common hierarchy

This commit migrates `AnnotationConfigReactiveWebApplicationContext`
parent to the `GenericApplicationContext` abstraction. Any use of
`AnnotationConfigWebApplicationContext` is also removed as it also
inherits from the `AbstractRefreshableApplicationContext` outdated
hierarchy.

A new `AnnotationConfigServletWebApplicationContext` context is
introduced instead, extending from `GenericApplicationContext` and
providing the counter part of the reactive context for the Servlet-based
web app tests.

See gh-16096

spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/autoconfigure/RemoteDevToolsAutoConfigurationTests.java

@@ -28,6 +28,7 @@ import org.springframework.boot.devtools.restart.MockRestarter;
 import org.springframework.boot.devtools.restart.server.HttpRestartServer;
 import org.springframework.boot.devtools.restart.server.SourceFolderUrlFilter;
 import org.springframework.boot.test.util.TestPropertyValues;
+import org.springframework.boot.web.servlet.context.AnnotationConfigServletWebApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
@@ -37,7 +38,6 @@ import org.springframework.mock.web.MockFilterChain;
 import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.mock.web.MockHttpServletResponse;
 import org.springframework.mock.web.MockServletContext;
-import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
@@ -58,7 +58,7 @@ public class RemoteDevToolsAutoConfigurationTests {
 	@Rule
 	public MockRestarter mockRestarter = new MockRestarter();
 
-	private AnnotationConfigWebApplicationContext context;
+	private AnnotationConfigServletWebApplicationContext context;
 
 	private MockHttpServletRequest request;
 
@@ -174,7 +174,7 @@ public class RemoteDevToolsAutoConfigurationTests {
 	}
 
 	private void loadContext(String... properties) {
-		this.context = new AnnotationConfigWebApplicationContext();
+		this.context = new AnnotationConfigServletWebApplicationContext();
 		this.context.setServletContext(new MockServletContext());
 		this.context.register(Config.class, PropertyPlaceholderAutoConfiguration.class);
 		TestPropertyValues.of(properties).applyTo(this.context);