Converters for contributions to systemapi and vendorapi

The module types in scope of this conversion are
1. cc_library and cc_library_shared (non-null llndk or stubs prop)
2. cc_library_headers (all)

For (2), we need some postprocessing on the results of the parser
bp2BuildParseBaseProps. This is necessary because arch and os specific
API exports need to be flattened and added to the generateed API headers
target along NoConfigAxis
e.g.
```
The api equivalent of
cc_library_headers (
  name = "lifoo",
  deps = select({
  	"//build/bazel/platforms/arch:arm": ["arm_deps"],
  	"//build/bazel/platforms/arch:arm64": ["arm64_deps"],
	}),
)
should be
cc_api_library_headers (
  name = "lifoo",
  deps = ["arm_deps", "arm64_deps"],
)
```

For (1), we also need to generate 1:many header api targets so that
arch-specific deps can propagate arch metadata to the top-level
api_domain rule

Test: go test ./bp2build
Test: go test ./cc

Change-Id: Ie40cba1ac8e89f290b3d926c190d5e93abd52859

android/module.go

@@ -915,9 +915,16 @@ type commonProperties struct {
 type CommonAttributes struct {
 	// Soong nameProperties -> Bazel name
 	Name string
+
 	// Data mapped from: Required
 	Data bazel.LabelListAttribute
 
+	// SkipData is neither a Soong nor Bazel target attribute
+	// If true, this will not fill the data attribute automatically
+	// This is useful for Soong modules that have 1:many Bazel targets
+	// Some of the generated Bazel targets might not have a data attribute
+	SkipData *bool
+
 	Tags bazel.StringListAttribute
 
 	Applicable_licenses bazel.LabelListAttribute
@@ -1305,7 +1312,12 @@ func (attrs *CommonAttributes) fillCommonBp2BuildModuleAttrs(ctx *topDownMutator
 		platformEnabledAttribute.Add(&l)
 	}
 
-	attrs.Data.Append(required)
+	if !proptools.Bool(attrs.SkipData) {
+		attrs.Data.Append(required)
+	}
+	// SkipData is not an attribute of any Bazel target
+	// Set this to nil so that it does not appear in the generated build file
+	attrs.SkipData = nil
 
 	moduleEnableConstraints := bazel.LabelListAttribute{}
 	moduleEnableConstraints.Append(platformEnabledAttribute)