devel/py-cogapp: update to 3.5.1

While here:
- rename from devel/py-cog to devel/py-cogapp per FreeBSD python ports
  naming policy
  The policy requires a python port name must match its
  upstream (PyPI) name.
- update WWW
- add LICENSE_FILE
- convert to pep517
- add DOCS option
- add do-test target and test-time dependencies

Changelog: https://github.com/nedbat/cog/blob/v3.5.1/CHANGELOG.rst

PR:		287670
Approved by:	apesternikov@page2rss.com (maintainer timeout; >3 weeks)