- Added set_prop to shell so that you can set it from shell.
- Added set_prop to sytem_app so that it can be updated in settings.

Bug: 34256441
Test: can update prop from Settings and shell. nfc and lights work with
ag/1833821 with persist.hal.binderization set to on and off. There are
no additional selinux denials.
Change-Id: I883ca489093c1d56b2efa725c58e6e3f3b81c3aa