Extended topology tests

With #855 (closed) and #909 (closed) we already have an initial mechanism for extracting the topology from systems that consist of multiple layers of 2D and surface components. In order to test and tune this process we need better test cases.

Because it is hard to find good examples in the production data, we should create test cases using ASE. The ase.build module has several tools for building such systems. We could add the following test cases:

• Single surfaces. One with a well-known structure (e.g. FCC) and another one with a more exotic surface direction using the surface-function.
• Single 2D structures. ASE has a tool for MoS2 and e.g. graphene or boron nitride is simple to build ourselves.
• Surface heterostructure. E.g. BCC on top of FCC.
• 2D heterostructure. E.g. boron nitride on top of graphene.
• 2D/surface heterostructure. E.g. graphene on top of a gold surface.

By building these systems ourselves, we will know exactly the intended decomposition and we can easily create tests. Introducing some "noise" to the structures will be necessary to make the cases more realistic, but this is easy with atoms.rattle().