[Refactor][UI/UX] Reducing permanent memory occupation from Starter Select and Pokédex

[Wlowscha]

What are the changes the user will see?

Why am I making these changes?

After the introduction of the internal Pokédex, existing issues on mobile due to excessive memory consumption have been exacerbated. This is, in large part, due to the fact that some heavy data structures in both the Pokédex and the Starter Select screen are permanently saved in memory. With the present changes, these structures are only saved in memory while either screen is open.

What are the changes from a developer perspective?

Screenshots/Videos

See comments

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)?

[Wlowscha]

Memory occupation before the changes (using dev tools on Edge):

After starting the game

After opening and closing the Pokédex

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Memory occupation after the changes (using dev tools on Edge):

After starting the game

After opening the Pokédex

After closing the Pokédex