[Bug] fixes: Dark Deal reducing transformed Pokemon's held item stacks to 1

[bjparker1226]

Fixes #4580

What are the changes the user will see?

When a Pokémon is transformed into a legendary during the Dark Deal mystery encounter, it will now keep the correct number of all its held items.

Why am I making these changes?

Fixes a bug

What are the changes from a developer perspective?

Makes sure the stack count of each item on the removed Pokémon gets passed when the boss legendary is configured.

Screenshots/Videos

Note Verizion has two stacks of Quick Claws. Prior to this change, they would have been reduced to 1.

How to test the changes?

Modified src/overrides.ts and src/data/mystery-encounters/encounters/dark-deal-encounter.ts to ensure the selected Pokémon was one with at least 2 of a held item. No automated tests were introduced.

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 considered writing automated tests for the issue?
• If I have text, did I make it translatable and add a key in the English locale file(s)?
• Have I tested the changes (manually)?
  • Are all unit tests still passing? (npm run test)
• Are the changes visual?
  • Have I provided screenshots/videos of the changes?

[flx-sta]

We should get a test covering that so it doesn’t break again