Add a new macro for products to make artifact path requirements.

When a product adds a path requirement, the build system will verify
that all its artifacts are produced inside these paths, and fail
otherwise.

The paths are all relative to PRODUCT_OUT, and the macro also supports
giving a whitelist, for known existing offenders in the hierarchy. The
build will fail if redundant whitelist entries are present.

Example invocation:
_paths := $(TARGET_COPY_OUT_SYSTEM)/
_whitelist := root/init root/init.rc
$(call require-artifacts-in-path $(_paths), $(_whitelist))

Bug: 80410283
Test: Downstream with a new product definition.
Change-Id: I235de681f65254087a42e345af69b2113b682072

core/product_config.mk

@@ -234,6 +234,12 @@ endif
 $(call import-products, $(current_product_makefile))
 endif  # Import all or just the current product makefile
 
+# Import all the products that have made artifact path requirements, so that we can verify
+# the artifacts they produce.
+$(foreach makefile,$(ARTIFACT_PATH_REQUIREMENT_PRODUCTS),\
+  $(if $(filter-out $(makefile),$(PRODUCTS)),$(eval $(call import-products,$(makefile))))\
+)
+
 # Sanity check
 $(check-all-products)