Importing swcore's testbench to the new repo: adding swcore testbench files from the old repo (hopefully with the history) to the new repo

Importing swcore to the new repo: adding swcore files from the old repo (hopefully with the history) to the new repo

Importing swcore to the new repo: removing swc_swcore_pkg.vhd to avoid conflicts, this file in the new repo is backward compatible with the file in the old repo