Introduce optimizeLocations flag for resource location filtering on startup

This flag is off by default since it requires jar files with directory entries.

Closes gh-27624

spring-webmvc/src/test/java/org/springframework/web/servlet/resource/ResourceHttpRequestHandlerTests.java

@@ -311,7 +311,7 @@ public class ResourceHttpRequestHandlerTests {
 		assertThat(this.response.getContentAsString()).isEqualTo("h1 { color:red; }");
 	}
 
-	@Test  // gh-27538
+	@Test  // gh-27538, gh-27624
 	public void filterNonExistingLocations() throws Exception {
 		List<Resource> inputLocations = Arrays.asList(
 				new ClassPathResource("test/", getClass()),
@@ -321,6 +321,7 @@ public class ResourceHttpRequestHandlerTests {
 		ResourceHttpRequestHandler handler = new ResourceHttpRequestHandler();
 		handler.setServletContext(new MockServletContext());
 		handler.setLocations(inputLocations);
+		handler.setOptimizeLocations(true);
 		handler.afterPropertiesSet();
 
 		List<Resource> actual = handler.getLocations();