fsverity_init is a new shell script that uses mini-keyctl for the actual
key loading. Given the plan to implement keyctl in toybox, we label
mini-keyctl as u:object_r:toolbox_exec:s0.
This gives us two benefits:
- Better compatibility to keyctl(1), which doesn't have "dadd"
- Pave the way to specify key's security labels, since keyctl(1)
doesn't support, and we want to avoid adding incompatible option.
Test: Boot without SELinux denial
Test: After boot, see the key in /product loaded
Bug: 128607724
Change-Id: Iebd7c9b3c7aa99ad56f74f557700fd85ec58e9d0