feat: Create A Box2D Physics Plugin

[quinton-ashley]

p5play, Construct 3, GDevelop, and Unity all use the Box2D physics simulator.

Matter.js is not a good physics simulator and was probably only used in kaboom.js due to device limitations years ago.

[niceEli]

As of right now the physics is plugin based. It would be best to do this and make accurate physics part of engine itself at the same time.

[mflerackers]

No, physics needs to be plugin based, because we need to support multiple physics engines. Box2D (or PlanckJS or MatterJS) are not a good choice for classic platform games because these games don't use or require realistic physics. So the physics engine will be a choice, not something built-in.
Depending on that choice, area and body will be behave differently, but their API will stay largely the same.