Resolve "CodeQL: Python issues"

This MR does the following:

• addresses most of the issues reported by CodeQL and all issues reported by black
• adds --seed option in gen_kea_config.py. The default behavior remains unchanged (randomize options in the generated config), but if the seed is specified, the randomization is repeatable and consistent
• extended the rake lint:python:black with the optional FIX=true parameter.

Closes #1264 (closed)