Consuming Arena Allocator for our Rendering

[JeanPhilippeKernel]

This PR integrates an Arena Allocator into the rendering engine to improve memory management, allocation efficiency, and performance across multiple subsystems. The changes touch core rendering paths, UI components, and data handling infrastructure.

Key Changes

• Arena Allocator Adoption: Core engine and UI code paths now use arena-based memory allocation, reducing fragmentation and improving performance.
• Editor Scene Refactoring: Significant restructuring of the editor scene for improved clarity, modularity, and maintainability.
• AssetManager Added: Introduction of an AssetManager to centralize and streamline asset loading, tracking, and management.
• GPU Buffer Pre-allocation: Pre-allocation strategies for GPU buffers implemented to minimize runtime allocations and stutter during scene loading or asset streaming.
• UI & Windowing: Updates and optimizations to UI components (log, inspector, hierarchy views) with arena-backed data structures.
• Drag-and-Drop Support: You can now drag and drop scene files and mesh files directly into the viewport to open them.

[jnyfah]

maybe in void init(Memory::ArenaAllocator* allocator, size_type initial_capacity, size_type initial_size) we can set initial_size to default to 0 so it can be optional

[JeanPhilippeKernel]

do/did we ever use that initial_size ? AFAIK I didn't see us using it - that's the reason I decided to drop it

[jnyfah]

static variable shared by ALL iterators wont this cause problem?