Setting camera target to most negative number to handle arbitrary large maps

[aaronchongth]

What's new

• Tweak camera target to most negative number to better accommodate almost-orthogonal view for extremely large maps
• refactored camera control to prevent creation of camera every time zoom changes

Self-checks

• [ ] I have prototyped this new feature (if necessary) on Figma
• [ ] I'm familiar with and follow this Typescript guideline
• [ ] I added unit-tests for new components
• [ ] I tried testing edge cases
• [ ] I tested the behavior of the components that interact with the backend, with an e2e test

[aaronchongth]

This changes the 3D position that the camera points towards, raising it to a large negative number implies that the camera will almost always be pointing down vertically, no matter where the camera is moved to in 3D space. This helps mimic an orthogonal view.

Although this value falls under the category of bigger-is-better, there's no harm in using the scene size to calculate it dynamically I guess.

I've also refactored the camera controls a little to reduce repeated construction of cameras and its controller

[aaronchongth]

As explained the purpose of these changes in DM