wayne-common: Add BOARD_PLAT_[PUBLIC|PRIVATE]_SEPOLICY_DIR

Move vendor policy to vendor and add a place for system extensions.
Also add such an extension: a labeling of the qti.ims.ext service.

Bug: 38151691
Bug: 62041272
Test: Policy binary identical before and after, except plat_service_contexts
has new service added.
Change-Id: Ie4e8527649787dcf2391b326daa80cf1c9bd9d2f

Change-Id: I1493c4c8876c4446a1de46b39942098bf49c79f8

BoardConfigCommon.mk

@@ -254,8 +254,9 @@ PROTOBUF_SUPPORTED := true
 
 # SELinux
 include device/qcom/sepolicy/sepolicy.mk
-BOARD_SEPOLICY_DIRS += \
-    $(COMMON_PATH)/sepolicy
+BOARD_SEPOLICY_DIRS += $(COMMON_PATH)/sepolicy/vendor
+BOARD_PLAT_PUBLIC_SEPOLICY_DIR += $(COMMON_PATH)/sepolicy/public
+BOARD_PLAT_PRIVATE_SEPOLICY_DIR += $(COMMON_PATH)/sepolicy/private
 
 # Treble
 PRODUCT_FULL_TREBLE_OVERRIDE := true