feat: update to use the original map file structure

[erickzanardo]

Description

Changes the map files to use the original structure sent by HOPR, that way, the map files can be edited directly from the game source base, without needing to change, parse anything.

Note about the gen.dart: Making the prefixes and bundles from flame work well with the generated Assets class was giving too much of a headache, so for now I decided to simply remove them, we can put that back again later when we have more time to think this through

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore