Add CI/CD for tenzir/zeek Docker image

[dominiklohmann]

This PR adds the missing CI pieces and automation to publish to Dockerhub.

[mavam]

This now fails with the following error:

Installing "zeek/j-gras/zeek-af_packet-plugin".error: incomplete installation, the follow packages failed to be installed:
#10 15.60   zeek/j-gras/zeek-af_packet-plugin (2.1.2)
#10 15.60 
#10 15.60 Failed installing "zeek/j-gras/zeek-af_packet-plugin": package build_command failed, see log in /opt/zeek/var/lib/zkg/logs/zeek-af_packet-plugin-build.log
#10 15.62 === STDERR ===
#10 15.62 CMake Error at CMakeLists.txt:22 (message):
#10 15.62   Kernel headers not found.
#10 15.62 
#10 15.62 
#10 15.62 === STDOUT ===

How come your fix to install linux-headers-generic has no effect?

[mavam]

Good to see you got it finally working!