Add dagger map for injecting DnsWriter implementations

This is one of several CLs in a sequence for allowing per-TLD DNS
implementations.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=129445641

java/google/registry/module/backend/BUILD

@@ -13,6 +13,12 @@ java_library(
         "//java/com/google/common/base",
         "//java/com/google/common/collect",
         "//java/com/google/common/net",
+        "//third_party/java/bouncycastle",
+        "//third_party/java/dagger",
+        "//third_party/java/joda_time",
+        "//third_party/java/jsr305_annotations",
+        "//third_party/java/jsr330_inject",
+        "//third_party/java/servlet/servlet_api",
         "//java/google/registry/backup",
         "//java/google/registry/bigquery",
         "//java/google/registry/billing",
@@ -20,6 +26,8 @@ java_library(
         "//java/google/registry/cron",
         "//java/google/registry/dns",
         "//java/google/registry/dns/writer",
+        "//java/google/registry/dns/writer/clouddns",
+        "//java/google/registry/dns/writer/dnsupdate",
         "//java/google/registry/export",
         "//java/google/registry/export/sheet",
         "//java/google/registry/flows",
@@ -34,12 +42,6 @@ java_library(
         "//java/google/registry/request:modules",
         "//java/google/registry/tmch",
         "//java/google/registry/util",
-        "//third_party/java/bouncycastle",
-        "//third_party/java/dagger",
-        "//third_party/java/joda_time",
-        "//third_party/java/jsr305_annotations",
-        "//third_party/java/jsr330_inject",
-        "//third_party/java/servlet/servlet_api",
     ],
 )