Update vectorization_logic tests for all platforms.

A few of the tests depend on packet (and half packet) availability, implementation of specific packet functions (e.g. add, div), and unrolling limits and costs, which can vary by platform. Here we add the ability to ignore the traversal or unrolling when it is not informative.

Also, with some half-packets, if the size of the packet is smaller than 16 bytes (e.g. Packet2f), then matrices of certain sizes no longer vectorize with EIGEN_UNALIGNED_VECTORIZE=0, since they are assumed unaligned. Adjusted matrix sizes in such cases to get the tests to pass.

This should help tests pass on all platforms. Tested with SSE, AVX, AVX512, NEON, AltiVec.