[web/test] port unittest_magicsearch to RepoAccess API
request created in setUp makes context manager usage painful, so create
a context manager to do the setup for each test class.
usr/lib/PY_VERSION/*-packages/cubicweb/entities/
usr/lib/PY_VERSION/*-packages/cubicweb/ext/
usr/share/cubicweb/cubes/
usr/lib/PY_VERSION/*-packages/cubicweb/*.py