Handle nameless modules during bp2build conversion.

So far it is `package` module.

Test: treehugger
Change-Id: Ibf3af0b0bf0a532e2ea1d478275a5ac3784ef170
diff --git a/bp2build/androidbp_to_build_templates.go b/bp2build/androidbp_to_build_templates.go
index 5fed4fa..9b21c32 100644
--- a/bp2build/androidbp_to_build_templates.go
+++ b/bp2build/androidbp_to_build_templates.go
@@ -23,7 +23,7 @@
 
 	// A macro call in the BUILD file representing a Soong module, with space
 	// for expanding more attributes.
-	soongModuleTarget = `soong_module(
+	soongModuleTargetTemplate = `soong_module(
     name = "%s",
     soong_module_name = "%s",
     soong_module_type = "%s",
@@ -31,10 +31,13 @@
     soong_module_deps = %s,
 %s)`
 
-	bazelTarget = `%s(
+	ruleTargetTemplate = `%s(
     name = "%s",
 %s)`
 
+	unnamedRuleTargetTemplate = `%s(
+%s)`
+
 	// A simple provider to mark and differentiate Soong module rule shims from
 	// regular Bazel rules. Every Soong module rule shim returns a
 	// SoongModuleInfo provider, and can only depend on rules returning