[aws-load-balancer-controller] Add support for multiple namespaces in watchNamespace

[ahmedsamer]

Description

This PR adds support for the watchNamespace parameter to accept multiple namespaces, addressing the limitation where the AWS Load Balancer Controller could only watch a single namespace.

Changes

• templates/deployment.yaml: Added logic to check if watchNamespace is a list and iterate through multiple namespaces
• README.md: Updated documentation to clarify that watchNamespace accepts both string and list formats
• values.yaml: Added examples demonstrating both single and multiple namespace configurations

Backward Compatibility

This change is fully backward compatible. Existing configurations using a string value will continue to work as before.

Usage Examples

Single namespace (existing behavior):

watchNamespace: my-namespace

Multiple namespaces (new feature):

watchNamespace:
  - namespace1
  - namespace2
  - namespace3

Testing

The template logic uses Helm's `kindIs "slice"` function to detect whether the value is a list, ensuring proper handling of both formats.

Closes

Closes #1306

[ahmedsamer]

Test Results

I've tested the changes locally with helm template:

Single namespace (string) - backward compatible:

helm template test . --set clusterName=test-cluster --set watchNamespace=my-namespace

Result:

- --watch-namespace=my-namespace

Multiple namespaces (list) - new feature:

helm template test . --set clusterName=test-cluster --set watchNamespace="{ns1,ns2,ns3}"

Result:

- --watch-namespace=ns1
- --watch-namespace=ns2
- --watch-namespace=ns3

Chart Version

The validation script indicates that the Chart version needs to be bumped from 3.2.1. Since this is a new feature (not a bug fix), should I bump it to:

• 3.3.0 (minor version bump for new feature)?
• Or would you prefer to handle versioning during the merge?

Please let me know and I'll update accordingly.