[P1][Beta] Fix phazing moves forcing switches into fainted/ineligible Pokemon

[PigeonBar]

What are the changes the user will see?

Phazing moves can no longer randomly choose to force a switch into a fainted/ineligible Pokemon.
Also, phazing moves properly use seeded RNG instead of unseeded RNG.

Why am I making these changes?

Bug report: Discord

What are the changes from a developer perspective?

1. Phazing moves now generate a list of indices of eligible Pokemon to switch into, and then randomly pick an eligible index using seeded RNG.
2. Added tests for Whirlwind and Dragon Tail.

Screenshots/Videos

Before the changes: Phazing moves can force a switch into a fainted Pokemon

20241129.Before.Fix.Phazing.mp4

After the changes: Phazing moves no longer force a switch into a fainted Pokemon

20241129.After.Fix.Phazing.mp4

How to test the changes?

1. Reach the floor 195 rival.
2. Defeat 4 of the rival's 6 Pokemon.
3. Use a phazing move.
4. The phazing move should always force the rival to switch to their only other unfainted Pokemon.

Checklist

• I'm using beta as my base branch
• There is no overlap with another PR?
• The PR is self-contained and cannot be split into smaller PRs?
• Have I provided a clear explanation of the changes?
• Have I tested the changes manually?
• Are all unit tests still passing? (npm run test)
  • Have I created new automated tests (npm run create-test) or updated existing tests related to the PR's changes?
• Have I provided screenshots/videos of the changes (if applicable)?
  • [ ] Have I made sure that any UI change works for both UI themes (default and legacy)?

Are there any localization additions or changes? If so:

• [ ] Has a locales PR been created on the locales repo?
  • [ ] If so, please leave a link to it here:
• [ ] Has the translation team been contacted for proofreading/translation?

[DayKev]

Just a minor style nit but otherwise seems good.

[torranx]

lgtm 🚀