Use only one Pixi renderer and stage for now

[#58090240]

So each viewport is defined by separate DisplayObjectCollection, but
they share common stage and renderer.
Implement radial bonds rendering using PixiJS

[#58090240]
Merge branch 'master' into pixijs-bonds

Conflicts:
  src/lab/common/views/svg-container.js
  src/lab/models/md2d/views/renderer.js
Increase canvas oversampling to 2

[#59417796]
Merge branch 'pixijs-bonds'