Implement GHCR container image build pipeline

[jujaga]

Description

This PR focuses on implementing a parallel Github Actions based image builder. While the old Jenkins pipeline depends on the image built by the buildconfig, we will be transitioning away from using that and instead storing our container artifacts in ghcr.io. This also updates our unit testing GA to test on Node 16, 18 and 20.

• 8a0a5c3 Implement GHCR container image build pipeline
• fc2c1b8 Extract Dockerfile from BuildConfig template

SHOWCASE-2755

Types of changes

New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING doc
• I have checked that unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have updated the OpenAPI 3.0 v*.api-spec.yaml documentation (if appropriate)
• I have added necessary documentation (if appropriate)

Further comments

[github-actions]

Coverage Report

Totals
Statements:	97.02% ( 750 / 773 )
Methods:	98.04% ( 100 / 102 )
Lines:	98.57% ( 415 / 421 )
Branches:	94% ( 235 / 250 )

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PR Deployed at: https://ches-dev-pr-123.apps.silver.devops.gov.bc.ca