feat: remove plugin order rendering config (z-index)

[aminya]

Fixes #759

There is unnecessary complexity in the decoration management/rendering code to render the decorations based on an order. However, this seems unnecessary to me as decorations can perfectly be shown on top of each other and they do not have conflicts. The default for all of them is 0 which means until today by default no ordering has been applied. But the code is still there slowing down the rendering.

This config does not make sense to me and just adds complexity and slow-down.