Add cc_library_headers support to bp2build.

Test: Added cc_conversion_test.go.
Change-Id: Id4459d2c2fa02687a374cd9fb25d687e9678218c

cc/library.go

@@ -27,6 +27,7 @@ import (
 	"github.com/google/blueprint/pathtools"
 
 	"android/soong/android"
+	"android/soong/bazel"
 	"android/soong/cc/config"
 )
 
@@ -120,6 +121,9 @@ type LibraryProperties struct {
 	// If this is an LLNDK library, properties to describe the LLNDK stubs.  Will be copied from
 	// the module pointed to by llndk_stubs if it is set.
 	Llndk llndkLibraryProperties
+
+	// Properties for Bazel migration purposes.
+	bazel.Properties
 }
 
 // StaticProperties is a properties stanza to affect only attributes of the "static" variants of a