Add minimal bp2build converter for combined apis

4 merged_txts targets will be generated for a combined_api target

Test: api_conversion_test.go and TH

Bug: 267600251
Change-Id: I8ec4a1073538c394a7eef896d8f6e354986fa2cd
diff --git a/api/Android.bp b/api/Android.bp
index a2b8038..20528f2 100644
--- a/api/Android.bp
+++ b/api/Android.bp
@@ -31,10 +31,12 @@
         "blueprint",
         "soong",
         "soong-android",
+        "soong-bp2build",
         "soong-genrule",
         "soong-java",
     ],
     srcs: ["api.go"],
+    testSrcs: ["api_test.go"],
     pluginFor: ["soong_build"],
 }