ci: introduce comprehensive CI/CD workflows for Helm charts

[O7EG]

This pull request introduces comprehensive CI/CD workflows for Helm charts, focusing on automation, code quality and developer experience. The main changes include the addition of GitHub Actions workflow definitions, local development helpers, as well as documentation to streamline chart development tasks:

• Add reusable composite actions for installing and running tools like Just, Typos, Committed and Helm.
• Introduce multiple GitHub Actions workflows for enforcement of project's commit style and PR naming conventions, CI, Helm chart validation, testing and release automation.
• Add a Justfile with recipes for common development tasks such as spell checking, Helm chart linting, validation, testing, dependency management and installation, Minikube cluster management and bootstrapping of a local EAASI deployment.
• Add configuration for automated changelog generation based on conventional commits and repository metadata.
• Provide initial documentation with EAASI-specific development workflow instructions.

These changes collectively aim to lay the foundation for a robust, automated, and contributor-friendly workflow for EAASI-specific Helm chart development and maintenance.

Closes: #3