feat: Support OCI registries

[adwk67]

Description

This PR covers the following:

• addition of the option --chart-source that enables charts to be pulled either from an OCI registry (the default) or a Nexus repository
• retrieves tags from Harbor or Nexus for operator list and describe commands

Caution

Do not merge & release before Jan 2025 as this will affect the kuttl tests.

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

Author

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1. Helm chart can be installed and deployed operator works
2. Tested commands with both options

Reviewer

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1. Code contains useful comments
2. (Integration-)Test cases added
3. Documentation added or updated
4. Changelog updated
5. Cargo.toml only contains references to git tags (not specific commits or branches)

Acceptance

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1. Feature Tracker has been updated
2. Proper release label has been added