bp2build: framework for generating BazelTargetModules.

This CL creates the framework necessary for generating
BazelTargetModules from regular Soong Android modules.
BazelTargetModules are code-generated into Bazel targets in BUILD files.

See the follow-up CL for examples of creating filegroup/genrule
BazelTargetModules.

Test: GENERATE_BAZEL_FILES=true m nothing # creates out/soong/bp2build
with no BUILD files, because there are no BazelTargetModules in the
module graph.

Change-Id: I33a96365bd439043b13af6db9e439592e9983188
diff --git a/bp2build/bzl_conversion_test.go b/bp2build/bzl_conversion_test.go
index 8bea3f6..01c7271 100644
--- a/bp2build/bzl_conversion_test.go
+++ b/bp2build/bzl_conversion_test.go
@@ -172,7 +172,7 @@
 			content: "irrelevant",
 		},
 	}
-	files := CreateBazelFiles(ruleShims, make(map[string][]BazelTarget))
+	files := CreateBazelFiles(ruleShims, make(map[string][]BazelTarget), false)
 
 	var actualSoongModuleBzl BazelFile
 	for _, f := range files {