Isolate customizable code in activity reporting

Modularize the code for DNS count reporting to allow it to be customized for
more flexible systems.
Tested:
  Uploaded to alpha with hacks to allow admin initiating and logging from the
  DnsCountQueryCoordinatorModule, verified that the provider function is invoked and
  that the action runs successfully.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=225225587

javatests/google/registry/util/TypeUtilsTest.java

@@ -52,4 +52,22 @@ public class TypeUtilsTest {
         .hasMessageThat()
         .contains("Failed to load class com.fake.company.nonexistent.Class");
   }
+
+  public static class ExampleClass {
+    String val;
+
+    public ExampleClass(String val) {
+      this.val = val;
+    }
+  }
+
+  @Test
+  public void test_instantiateWithArg() {
+    Class<ExampleClass> clazz =
+        TypeUtils.getClassFromString(
+            "google.registry.util.TypeUtilsTest$ExampleClass", ExampleClass.class);
+
+    ExampleClass result = TypeUtils.instantiate(clazz, "test");
+    assertThat(result.val).isEqualTo("test");
+  }
 }