kube: Enhance configuration validation with new Slack channel and nam…

…espace checks

- Introduced functions for validating Slack channel names and Kubernetes namespace names, improving configuration validation accuracy.
- Replaced previous validation methods with custom regex-based checks for better error reporting and adherence to naming conventions.
- Removed unused import from health.go to streamline the codebase.

Signed-off-by: NotHarshhaa <reddyharshhaa12@gmail.com>

kube: Update release-chart workflow for GitHub CLI integration

- Changed permissions to allow write access for contents and packages.
- Replaced chart-releaser installation with GitHub CLI installation for better release management.
- Updated the release process to create GitHub releases directly using the GitHub CLI, including dynamic release notes and chart file handling.

Signed-off-by: NotHarshhaa <reddyharshhaa12@gmail.com>

kube: Refactor Helm template for image name generation

- Updated the Helm template to handle image registry and repository more robustly by adding default values.
- Improved the logic for generating image names based on the presence of image digests and registries, enhancing flexibility and clarity.

Signed-off-by: NotHarshhaa <reddyharshhaa12@gmail.com>