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)