k8s: Create docker init container

[hannahramadan]

We need to create a docker container that contains an agent’s code for a particular agent version

Some languages already have examples, forked from OTel, and we can use these as inspiration.

Additional Context:
A new GHA workflow will be created in a shared repository (auto-init-containers-releases) that polls for a new agent releases every hour and publishes init containers when a new agent release is found. #2571

[workato-integration]

https://new-relic.atlassian.net/browse/NR-264597