Update OTA to understand SELinux filesystem labels

Make fs_config aware of SELinux contexts, and output the context
whenever we output the UID / GID / file perms.

Pass the selinux context to the set_perm2() and set_perm2_recursive()
calls. When the OTA script fixes up filesystem permissions, it will
also fix up the SELinux context on the files.

Bug: 8985290
Change-Id: I6419b64c06309a93ac6b2f2cf9fc7f8815adeaf3