Scan for redundant decision triggers

[Alpinia]

Decisions have a trigger hierarchy (allowed -> visible -> available), so any triggers on the ones before don't need to be repeated in the latter ones - the only exception being visible and target_trigger, which need to be equal to one another.

In the above case, the available is completely redudant, as the conditions are already being met if the decision is visible.

[CaesarVincens]

It can be useful to duplicate the available triggers since those show up in the tooltip for the player, but sometimes you may not want the decision to be visible until it is also available.

For more context (perhaps for tooltips), and please correct me if I go wrong:
Allowed is a single check that tells the game whether to check this decision further. Mostly this is best done to limit decisions to certain tags.
Visible is whether to show the decision
Available is whether the decision can be taken.
These terms are used in ideas (specifically for ministers, etc.) also and tech.