Cleaner frogs

[TheSaddestGoomba]

Summary

None

Purpose of change

Revival of #74240 into the first of several smaller PRs.
Shrink JSON related to amphibian monsters and eggs.

Describe the solution

-Remove redundant mutant eggs and tadpoles
-Replace them by having tadpoles upgrade into monster_groups that include both their natural adult forms and mutant precursor forms
-This effectively shifts the 'mutation point' from fertilization/egg laying to metamorphosis. Natural frogs will no longer lay mutant eggs, instead natural tadpoles may now upgrade into mutants

Describe alternatives you've considered

An over-scoped omnibus PR (#74240) that should be broken up for best practices and for my own sanity.

Testing

Loaded up changes into a fresh world with no errors.

Additional context

Reimplemented from: #74240
Continuation of: #67029

[Karol1223]

I think this can still follow what I'm doing in #76211 because the tadpoles cannot be butchered anyway, right? Could you use the same odds I'm using there so we have consistency across vertebrate mutants? So 5% for a mutant outcome

[github-actions]

Spell checker encountered unrecognized words in the in-game text added in this pull request. See below for details.

Click to expand

• This tadpole's expanded size only eccentuates its other unique feature. Its tail fin is a vibrant gradient of crimson to yellow.

This alert is automatically generated. You can simply disregard if this is inaccurate, or (optionally) you can also add the new words to tools/spell_checker/dictionary.txt so they will not trigger an alert next time.

Hints for adding a new word to the dictionary

• If the word is normally in all lowercase, such as the noun word or the verb does, add it in its lower-case form; if the word is a proper noun, such as the surname George, add it in its initial-caps form; if the word is an acronym or has special letter case, such as the acronym CDDA or the unit mW, add it by preserving the case of all the letters. A word in the dictionary will also match its initial-caps form (if the word is in all lowercase) and all-uppercase form, so a word should be added to the dictionary in its normal letter case even if used in a different letter case in a sentence.
• For a word to be added to the dictionary, it should either be a real, properly-spelled modern American English word, a foreign loan word (including romanized foreign names), or a foreign or made-up word that is used consistently and commonly enough in the game. Intentional misspelling (including eye dialect) of a word should not be added unless it has become a common terminology in the game, because while someone may have a legitimate use for it, another person may spell it that way accidentally.

[TheSaddestGoomba]

I think this can still follow what I'm doing in #76211 because the tadpoles cannot be butchered anyway, right? Could you use the same odds I'm using there so we have consistency across vertebrate mutants? So 5% for a mutant outcome

Correct as far as I know, all of the non-giant tadpoles have the "NO_CORPSE" death function inherited and the two added in this are giant, so use the existing 'mutant_animal_noskin'. I shouldn't need to touch harvest with this PR

I agree that it's too high currently; almost guaranteed at least one in each egg drop. I think 10% is more fitting.
I do think it's appropriate for amphibians to have a higher overall rate of mutation than mammals, given their biology. They're more susceptible for a number of reasons including their exposure to the open environment during much more of their development, the rapid metamorphosis phase, and their more permeable skin as adults. Aside from The Big Badness itself, developing mammals are much more insulated from any secondary and environmental factors of mutation.

I plan to address the whole evo/repro cycle in a separate PR. Since there's more need for abstraction with thousands of frog eggs, the rate may need further adjusting. If, for instance, the rot_spawn_chance of the associated egg is reduced to represent the low survival rate of frog eggs and larva