Add dagger map for injecting DnsWriter implementations

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

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

java/google/registry/tools/BUILD

@@ -45,6 +45,7 @@ java_library(
         "//java/com/google/common/util/concurrent",
         "//java/google/registry/bigquery",
         "//java/google/registry/config",
+        "//java/google/registry/dns/writer",
         "//java/google/registry/export",
         "//java/google/registry/flows",
         "//java/google/registry/keyring/api",