Refactor 3D tool bar to be more like the 2D one

[Shadowblitz16]

Describe the project you are working on: ImageEditor addon

Describe the problem or limitation you are having in your project: Not really related but I am unsure how to structure my toolbar to match 2d and 3d view since they are different slightly

Describe the feature / enhancement and how it helps to overcome the problem or limitation: The 3D toolbar is not exactly like the 2D toolbar even though the basically have the same logic here are some things different..

• 2d view can't have multiple viewports
• 3d and 2d view have icons in different places
• 3d view doesn't have grid on top and left relative to camera view
• 3d and 2d have snap settings in different places
• 3d is missing some tools like...
  • change objects rotation pivot tool
  • pan tool
  • measure tool
  • bone tool
  • use grid snap tool

here are some pics on how they are diffrent.. Sorry about that one pic I couldn't capture the whole popup

Describe how your proposal will work, with code, pseudocode, mockups, and/or diagrams: I don't have any mockups but the idea would be that they would be the same

If this enhancement will not be used often, can it be worked around with a few lines of script?: Yes Also idk about that few lines of script I don't think you can.

Is there a reason why this should be core and not an add-on in the asset library?: I think it would make 2d and 3d editing more consistent and easier to learn the 3d scene editor when your have just used the 2d one.

I know I had trouble finding where things where at when I first star6ted using the 3d scene editor.

[aaronfranke]

Related: #2384 (should likely be solved first as it's a simpler issue, likely can be considered a subset of this one).