GridTools/GridGenerator: add some functions to support dim-independent programming

[nfehn]

The functions rotate() and extrude_triangulation() are currently only implemented for dim=2 or 3. This PR allows to write code that can be compiled for dim=2,3.

[drwells]

The changes to rotate make sense but I'm not so sure about extrusion. What case did you find where we need an additional extrusion overload?

[nfehn]

I get this error message

error: no matching function for call to extrude_triangulation(dealii::Triangulation<2, 2>&, unsigned int, const double&, dealii::Triangulation<2, 2>&)

[drwells]

Sure, but what does the call site look like?

[nfehn]

something like this
Triangulation<2> tria_2d; Triangulation<dim> tria_dim; GridGenerator::extrude_triangulation(tria_2d, foo, bar, tria_dim);

[nfehn]

@drwells Did I answer your questions? Please let me know if I still misunderstood something.

[drwells]

Sorry, I meant to get back to you on this. I think this is fine but we need to add documentation explaining the extrude is only available for 2D to 3D.

[tjhei]

I think this is fine

I also think that it is a bit weird but it does help make user code much simpler without having to rely on constexpr if (my code that uses extrude() always contains specialization based on dimension because of this).

[drwells]

/rebuild

[kronbichler]

Can you add this line back in? We typically tend to keep three empty lines between function implementations for readability, see here: https://dealii.org/developer/doxygen/deal.II/CodingConventions.html (style issues, no 4). Similarly also between the new function and the old one below.

[kronbichler]

Looks good apart from the empty lines.