Add Playground

[zardoy]

Hey! How do you currently test rendering or other changes in general in the viewer? I feel a need for some kind of playground where I can select things, ensure they are preserved, and I can share the state with other devs. Here is what I made:

This thing really speeds up fixing rendering issues & general development. The reason I'm opening this is to gather some kind of feedback on it, maybe there are actually simpler ways to test things around

Since I personally have it pwc atm I'm going to host it in the same place. Also, added a way to copy the playground link from pwc of the looking block, should be useful

Let me know if you want it, will open pr with esbuild configs

[rom1504]

seems interesting but we need to design things so this doesn't bloat this lib