Add Apache5, give highest priority

This commit updates `ClasspathSdkHttpServiceProvider` to give
`Apache5HttpClient` the highest preference for sync HTTP clients. If
`apache5-client` is on the classpath, Sync SDK clients not not
explicitly configured with an HTTP client will use Apache 5.

Author: dagnir

.changes/next-release/feature-AWSSDKforJavav2-d5acff4.json

@@ -0,0 +1,6 @@
+{
+    "type": "feature",
+    "category": "AWS SDK for Java v2",
+    "contributor": "",
+    "description": "Make `Apache5HttpClient` the preferred default HTTP client for sync SDK clients. This means that when `apache5-client` is on the classpath, and an HTTP client is *not* explicitly configured on client builder, the SDK client will use `Apache5HttpClient`."
+}

core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/http/loader/ClasspathSdkHttpServiceProvider.java

@@ -38,9 +38,10 @@ final class ClasspathSdkHttpServiceProvider<T> implements SdkHttpServiceProvider
 
     static final Map<String, Integer> SYNC_HTTP_SERVICES_PRIORITY =
         ImmutableMap.<String, Integer>builder()
-                    .put("software.amazon.awssdk.http.apache.ApacheSdkHttpService", 1)
-                    .put("software.amazon.awssdk.http.urlconnection.UrlConnectionSdkHttpService", 2)
-                    .put("software.amazon.awssdk.http.crt.AwsCrtSdkHttpService", 3)
+                    .put("software.amazon.awssdk.http.apache5.Apache5SdkHttpService", 1)
+                    .put("software.amazon.awssdk.http.apache.ApacheSdkHttpService", 2)
+                    .put("software.amazon.awssdk.http.urlconnection.UrlConnectionSdkHttpService", 3)
+                    .put("software.amazon.awssdk.http.crt.AwsCrtSdkHttpService", 4)
                     .build();
 
     static final Map<String, Integer> ASYNC_HTTP_SERVICES_PRIORITY =