net-mgmt/py-snmp4{-apps,-mibs}: Rename to match canonical upstream name

[kai]

Summary

PR 235120

Rename the following ports

• net-mgmt/py-snmp4 -> net-mgmt/py-pysnmp
• net-mgmt/py-snmp4-apps -> net-mgmt/py-pysnmp-apps
• net-mgmt/py-snmp4-mibs -> net-mgmt/py-pysnmp-mibs

Bump PORTREVISION for net/exaddos + net-mgmt/py-pysmi

Test Plan

poudriere (11.2-, 12.0-RELEASE, 13.0-CURRENT@r342772 amd64 + i386) for each py27 + py36 flavor -> OK

Runtime tests so far ok with one exception at net/exaddos, that brings:

This program requires python netsnmp

pip install pysnmp
pip install pysnmp_mibs

But this issue occurs also without the patches applied so it's unrelated to the renaming of the ports. Of course it should be investigated further after the patch has been committed.

[kai]

I forgot one thing: The Makefile in net-mgmt needs also to be updated.