Use local topology information while removing global numbering dependencies in Mesh.

Mainly replaces the Mesh::isNonlinear with Mesh::hasNonlinearElement, the latter relying only on local element information, and rewriting Mesh::getNumberOfBaseNodes. Other removals are just cleanup of no longer need _n_base_nodes variable.

Closes !3780 (closed) Fixes #3161 (closed)

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