fix(CI): Optimized workflows to build images based on file changes

[anurag-rajawat]

Description

This PR improves our CI & CD pipeline by:

• Adding dependabot.yml to automate dependency updates.
• Building and pushing container images only when relevant files change.
• Introducing two types of container images:
  • Versioned Images (e.g., v0.1): These images are released as part of stable releases.
  • Latest Images: These images are built and pushed whenever changes are made to the main branch.
• Adding a grype image scanning job to detect vulnerabilities in container images.

Does this PR introduce a breaking change?
No.

Checklist

• PR title follows the <type>: <description> convention
• I use conventional commits in my commit messages
• I have updated the documentation accordingly
• I Keep It Small and Simple: The smaller the PR is, the easier it is to review and have it merged
• I have performed a self-review of my code
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Additional information for reviewer

Mention if this PR is part of any design or a continuation of previous PRs

[VedRatan]

@anurag-rajawat you need to update the nimbus image version here so that the versioned image is being pushed in kind cluster, else kind cluster will be unable to find the image, similarly do that for nimbus-kubearmor nimbus netpol nimbus-kyverno adapter's images

[anurag-rajawat]

@VedRatan thank you very much for saving my time.

[VedRatan]

LGTM

[VedRatan]

LGTM merging it now. Thanks @anurag-rajawat