P0lskay/issue182 Add support for customizable labels on Vector resources

[P0lskay]

1. Customizable labels on Vector resources: We've added the ability to modify labels on Vector resources, providing more flexibility in managing and filtering resources.
2. New method for selector labels: To avoid potential immutability issues with the selector field in DaemonSet resources, we've created a separate method that returns a set of labels specifically for selectors. This ensures that the operator can safely update labels without encountering errors.
3. New field for labels in Vector and VectorAggregator CRDs: We've added a new labels field to the Vector and VectorAggregator CRDs, allowing users to specify custom labels for these resources.
4. Updated documentation: We've added information about label and annotation parameters to the documentation, providing users with clear guidance on how to utilize these features.
5. These changes enhance the overall functionality and usability of the Vector Operator, making it easier for users to manage and customize their Vector resources.

Related issues: #182

Changes:

• Added labels field to Vector and VectorAggregator CRDs
• Introduced a new method for returning selector labels
• Updated documentation to include information on label and annotation parameters
• Modified the operator to support customizable labels on Vector resources

[dkhachyan]

Thank you for the pull request!

I've reviewed it and everything looks good. Maybe we could create a separate function for adding labels? Something like this:

func AddLabels(dst, src map[string]string) {
    if dst == nil {
        dst = make(map[string]string)
    }
    
    for k, v := range src {
        if _, ok := dst[k]; !ok {
            dst[k] = v
        }
    }
}

We could save it here, for example:
https://github.com/kaasops/vector-operator/blob/main/internal/utils/k8s/label.go

[P0lskay]

@dkhachyan Great idea, thanks! I have already added the function of merging labels in commit 187e41b. If it's ok, then I think we can merge this PullRequest.

[dkhachyan]

LGTM