tests: Add Wycheproof ECDSA vectors

Adds a test using the Wycheproof vectors as outlined in bitcoin-core#1106. The
vectors are pulled from the Wycheproof repo using a python script to
emit C code. The script is embedded as a comment.

Co-authored-by: Sean Andersen <6730974+andozw@users.noreply.github.com>