Implement query parameter filtering for ListWebBrokerApis endpoint

Summary

The ListWebBrokerApis handler (gateway/gateway-controller/pkg/api/handlers/webbroker_api_handler.go) currently accepts query parameters displayName, version, and status (via api.ListWebBrokerApisParams) but ignores them, always returning all WebBrokerApi configurations.

A TODO comment in the code already documents this gap.

Expected Behavior

When the caller provides any of the following query parameters, the response should be filtered accordingly:

• displayName — filter by display name (case-insensitive string match)
• version — filter by version (exact or case-insensitive match)
• status — filter by deployment state (e.g., Deployed / Undeployed)

References

• PR introducing this handler: https://github.com/wso2/api-platform/pull/1954
• Related review comment: https://github.com/wso2/api-platform/pull/1954#discussion_r3239562665
• Related work tracked in: https://github.com/wso2/api-platform/pull/1944

Requested by

@senthuran16