Allow system app and update_engine to read OTA from /vendor

Introuducing vendor_boot_ota_file which will be used to allow
reading OTAs from /vendor/boot_otas when BOARD_16K_OTA_MOVE_VENDOR := true
is set. These OTAs will be read from settings app(system_app) and update
engine.

Test: m, m Settings && adb install -r $ANDROID_PRODUCT_OUT/system_ext/priv-app/Settings/Settings.apk
Bug: 335022191
Change-Id: Ie42e0de12694ed74f9a98cd115f72d207f67c834
diff --git a/private/file_contexts b/private/file_contexts
index c72d752..b82b4f0 100644
--- a/private/file_contexts
+++ b/private/file_contexts
@@ -437,6 +437,8 @@
 
 /(vendor|system/vendor)/etc/aconfig(/.*)?                      u:object_r:vendor_aconfig_storage_file:s0
 
+/vendor/boot_otas(/.*)?                                        u:object_r:vendor_boot_ota_file:s0
+
 # HAL location
 /(vendor|system/vendor)/lib(64)?/hw            u:object_r:vendor_hal_file:s0