Implement login/logout commands

Refactor the auth code into its own dagger module, add tests and use the new interfaces to implement the login and logout commands.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=149108266

java/google/registry/tools/RegistryTool.java

@@ -89,6 +89,8 @@ public final class RegistryTool {
           .put("list_reserved_lists", ListReservedListsCommand.class)
           .put("list_tlds", ListTldsCommand.class)
           .put("load_snapshot", LoadSnapshotCommand.class)
+          .put("login", LoginCommand.class)
+          .put("logout", LogoutCommand.class)
           .put("make_billing_tables", MakeBillingTablesCommand.class)
           .put("pending_escrow", PendingEscrowCommand.class)
           .put("publish_detail_report", PublishDetailReportCommand.class)