Add BOARD_MOVE_GSI_AVB_KEYS_TO_VENDOR_BOOT as a soong config variable

This variable allow customizing whether the `ramdisk` and
`vendor_ramdisk` are included in the boot image (ramdisk) or the
vendor boot image (vendor_ramdisk). This is useful for devices that
move recovery resources to the vendor boot partition

Bug: 347636127
Test: Add it to soong_config_module_type
Change-Id: If7a126fe8bdc69173921c0b01f85fb9480f4a36f