Show how close bodies are to rotting (#23530)

Show how close bodies are to rotting (#23530)

* Show how close bodies are to rotting

When examining a dead body, you will be able to see of close
it is to rotting.

 - "It still looks fresh.", in the first third of the pre-rot period
 - "It looks ripe.", in the second third
 - "It's starting to look bad.", in the last third

This could help players prioritize medical care.

* Alter the wording of the pre-rot indicator

* Use numeric rotting stages in FTL

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Co-authored-by: Kevin Zheng <kevinz5000@gmail.com>