Add requirements.txt files in test directories These files, located in each test directory (when needed), list test dependencies supplementary to install requirements. Some requirements.txt files include psycopg2 because it won't get installed by logilab-database apparently. Related to #5447161.

Pygments
#fyzz XXX pip install fails
cubicweb-card
cubicweb-file
cubicweb-localperms
cubicweb-tag