[Bug] Fix Early Bird

[DayKev]

What are the changes the user will see?

Early Bird will now appropriately reduce the number of sleep turns in all cases.

Why am I making these changes?

Discord bug report:

What are the changes from a developer perspective?

Sleep's cureTurn refactored to turnsRemaining and Early Bird now reduces it by an extra 1 each turn (implementation inspired by/copied from Showdown's). Relevant changes in ability.ts and move-phase.ts.

How to test the changes?

npm run test early_bird npm run test status-effect npm run test will_o_wisp

Checklist

• [x] I'm using beta as my base branch
• [x] There is no overlap with another PR?
• [x] The PR is self-contained and cannot be split into smaller PRs?
• [x] Have I provided a clear explanation of the changes?
• [x] 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)?~
• [x] Have I tested the changes (manually)?
  • [x] Are all unit tests still passing? (npm run test)
• ~[ ] Are the changes visual?~
  • ~[ ] Have I provided screenshots/videos of the changes?~