Export ProductBuildVendorBootImage to soong

Also add a file list file for vendor_ramdisk to compare against the
soong-built one.

Bug: 377563622
Test: Presubmits
Change-Id: I1842f767c3e560de1d11e024a7c918542e31095d
diff --git a/core/soong_config.mk b/core/soong_config.mk
index c5dd320..7c07010 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -430,6 +430,7 @@
   # boot image stuff
   $(call add_json_bool, BuildingRamdiskImage, $(filter true,$(BUILDING_RAMDISK_IMAGE)))
   $(call add_json_bool, ProductBuildBootImage, $(filter true,$(PRODUCT_BUILD_BOOT_IMAGE)))
+  $(call add_json_str, ProductBuildVendorBootImage, $(PRODUCT_BUILD_VENDOR_BOOT_IMAGE))
   $(call add_json_bool, ProductBuildInitBootImage, $(filter true,$(PRODUCT_BUILD_INIT_BOOT_IMAGE)))
   $(call add_json_bool, BoardUsesRecoveryAsBoot, $(filter true,$(BOARD_USES_RECOVERY_AS_BOOT)))
   $(call add_json_str, BoardPrebuiltBootimage, $(BOARD_PREBUILT_BOOT_IMAGE))