Fix robusted dionas not being recoverable (#21636)

* Fix robusted dionas not being recoverable

* Implement a polymorph cooldown field, used for TreeMorph

Allows the polymorphed Diona some time to work off robust harvest
without immediately polymorphing again.

* Minor adjustment to polymorph cooldown timing

* Apply suggestions from code review

Co-authored-by: Kara <lunarautomaton6@gmail.com>

* fix: trigger polymorph revert on destruction

As suggested by mirrorcult, DamageThresholdReached is not the ideal
candidate for reverting a polymorph on destruction, as there exists a
DestructionEventArgs to listen for instead.

---------

Co-authored-by: Kara <lunarautomaton6@gmail.com>

Resources/Prototypes/Polymorphs/polymorph.yml

@@ -101,7 +101,8 @@
   forced: true
   transferName: true
   revertOnDeath: true
-
+  inventory: Drop
+  cooldown: 160
 
 # this is the monkey polymorph for artifact.
 - type: polymorph