Add Polygon shape with variable amount of sides

[Jefwillems]

• [x] Provide an additional or update an example to demonstrate your changes or new features.
• [ ] Update the documentation if you introduced new behavior or changed existing behavior.
• I didn't update the documentation yet because i am expecting to make more changes to the bounding boxes/sizes.
• [x] This provides a solution for #3595
• This issue asked for diamond shapes with the label inside, this is possible now with options: {sides:4, shape:'polygon'}
• [x] Expect review comments and change requests by reviewer.
  • Please inspect the behaviour i added to the network basicUsage.html example, i believe i'm doing something off with the sizes/boundingbox
• [ ] Delete this checklist from your pull request. 🙃