security/py-pnu-certwatch: new port

The certwatch utility monitors X509 certificates expiration dates by
processing one or more data files containing lists of hostnames with
optional port numbers.

It's mainly used to check the expiration date of HTTPS certificates
(which is the default target when the port number is not indicated),
but the tool is protocol-agnostic and can "talk" to any SNI-aware
(Server Name Information) SSL/TLS server (smtps, imaps, ldaps, etc.)
without making too much assumptions on the correctness of servers
certificates.

The certificates can be saved to a specified directory for further
analysis with other tools (such as OpenSSL).

The tool's results are presented as text tables.

The main one is the list of certificates successfully fetched, ordered
by expiration date. This list can be filtered to only show
certificates expired or expiring within the specified number of days.

The second table is the sorted list of hostnames / hostports where
certificates couldn't be fetched, with our best attempts to identify
the reason why.

Two additional tables can be generated in order to print the common
names and alternate names unmentioned in your input data files.

Finally, for user convenience, all these reports can be generated in a
single multi-tabs Excel workbook.

PR: 277970
Approved by: maintainer, bapt (mentor)