Improve line rendering code

[LogicalError]

We have line rendering code that can render lines with a given thickness and optionally with dashes, but it's imperfect and can definitely be done better more efficiently and have better quality visuals

We should rewrite this and use this everywhere and remove all dependencies on unity line rendering code.
This could then also be used for runtime editing

[babooncodes]

You should probably have an IRenderer that has an implementation for unity, using a commandbuffer that constructs line mesh, similar to https://github.com/realgamessoftware/dear-imgui-unity/blob/master/ImGuiNET.Unity/Renderer/ImGuiRendererMesh.cs

[LogicalError]

@baboongd that would make a lot of sense! The current line rendering code was written before all of this was available in Unity, so it couldn't take advantage of it. But now it definitely makes sense to use Compute buffers to create the line geometry