perf: skip repeatedly traversing the same derived

[dummdidumm]

This introduces a new flag which marks a derived as visited during the mark_reaction phase and lifts it during the dirty-check/execution phase (both are necessary because not all deriveds are necessarily executed, but they're always checked).

We could've used a Set on mark_reactions which would've been simpler to reason about, alas it was performing consistenly worse on the kairo_mux_unowned / kairo_mux_owned benchmarks (it kinda makes sense generally, creating and filling a set is more expensive than juggling flags).

Closes #16658, which showcases are particularly gnarly signal graph where many deriveds point to the same deriveds, where we would be traversing the same reactions over and over if we didn't do this.

I also added a similar measure (this time a set/map is unavoidable/makes more sense) for mark_effects, hopefully this helps for #16990

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