[WIP] Fix Compilation Errors

[jh66637]

I think there are compilation errors related to explicitly using double and dealii/dealii#14142

[nfehn]

hm, it is actually a design goal in ExaDG to keep Number out of data structures such as BoundaryDescriptor. I am not sure if the changes here are the way how we should approach this.

[jh66637]

I am currently just checking where the error comes from. I am not intending to keep all the changes

[jh66637]

@nfehn The problem is, that deal checks internally for double vs float. So instantiating InterfaceCoupling will fail. So you should not be allowed to call InterfaceCoupling and InterfaceCouplingData with Number==float in the first place if only doubles are supported inside.

[jh66637]

To be able to keep Number out, we need something like a copy of float data to double data. Or a major code refracturing. I might give it a try again towards the end of the week and create an Issue in the mean time.