AndroidSystemSEPolicy

Switch from /data/misc/reboot/last_reboot_reason to persistent
Android property persist.sys.boot.reason for indicating why the
device is rebooted or shutdown.

Introduce protection for all boot reason properties

Protect the following properties with these labels

ro.boot.bootreason      u:object_r:bootloader_boot_reason_prop:s0
sys.boot.reason         u:object_r:sys_boot_reason_prop:s0
persist.sys.boot.reason u:object_r:last_boot_reason_prop:s0

Setup the current as-need access rules for each.

ToDo: Remove u:object_r:reboot_data_file after internal fixes.

Test: system/core/bootstat/boot_reason_test.sh
Bug: 64687998
Change-Id: I3771c73933e8ae2d94aee936c7a38b6282611b80