fixed IACT dependency issue (sink, bh, star, RT)

Fixes #771 (closed).

Here's a pre-fix dependency plot of the step where my test in #771 (closed) crashed:

And one after:

We have more stars_in and stars_out unlocks now. Also noteably this fixes an issue I wanted to tackle next: Now the hydro-type tasks of the RT section (gradient and transport) have the same number of unlocks as the hydro tasks themselves; and the star-type tasks of the RT section (inject) have the same number of unlocks as the star tasks. So this'll get two birds with one stone, at least for me.