[Refactor] Move fixed battle configs and some enums to separate files

[Fontbane]

What are the changes the user will see?

• None

Why am I making these changes?

• Organization
• Easy access for balance team

What are the changes from a developer perspective?

• Moves the enums:
  • BattleType to enums/battle-spec
  • ClassicFixedBossWaves to enums/fixed-boss-waves
  • Also uses ClassicFixedBossWaves in more places where appropriate
• Moves fixed battle configs to data/balance/fixed-battle-configs
• Fixed indentation on TurnCommand interface

Screenshots/Videos

How to test the changes?

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?