init/selinux: renames nonplat_declaration.cil to plat_pub_versioned.cil

The content of nonplat_declaration.cil in /vendor is a versioned public
sepolicy exported from ${AOSP}/system/sepolicy/public. Renames it to
better reflect the fact.

Bug: 64240127
Test: boot sailfish normally without odm
Test: boot another device having odm
Change-Id: I654f5bbde2f2d666a2a5c7ed8561ccd93c983a6e