CI/CD: Use workflow_run Event to create dependencies between CI/CD Workflows

[mrzzy]

Problem

Currently, the CI/CD workflows run independently and concurrently of each other:

• Since ordering is not defined, CD could run before the CI, potentially deploying bad artifacts which could have been caught by the tests run by the CI.
• There is duplication of code between the workflows. ie all 3 workflows build the bentobox-engineimage from scratch.

Proposal

• Introduce workflow dependency by triggering CD when CI completes with the workflow_run event:
• Move all building of artifacts to CI, CD to use built artifacts from CI.