Move implementation of LocalFiniteElement Cache to dune-localfunctions

Summary

This moves some internal details of a dynamic local-finite-element cache to dune-localfunctions and additionally adds a FixedGeometryType cache.

Merge requirements

• core/dune-localfunctions!248 (merged)
• core/dune-localfunctions!286 (merged) (bugfix for python bindings)
• Improve the definition of the dynamic Lagrange basis, by specifying a storage and compute field type