Axe the if-what jungle in rpmfiDecideFateIndex()

Axe the if-what jungle in rpmfiDecideFateIndex()

- Unless the file does not exist on disk, we cannot determine the
  correct action for config files and symlinks before we actually
  check them. Those are also the only types that *can* result in
  FA_ALTNAME/FA_SAVE action, anything else we can just create.
  Besides making the logic a whole lot easier to follow, it also
  fixes our remaining test-case failures. Who would've thought?
- Might be worth noting that this requires the pile of fsm fixes
  from previous commits to work.