feat(kong): add additionalProxies support for multiple proxy services

[maratsal]

What this PR does / why we need it:

Support multiple proxy services when in addition to default proxy service, users want to deploy extra service with different config.

Which issue this PR fixes

Add support for defining multiple proxy services from a single Helm values configuration via the new 'additionalProxies' map in values.yaml.

Each entry in additionalProxies creates a separate Kubernetes Service that routes to the same Kong proxy container, enabling use cases like:

• External LoadBalancer with proxy_protocol (e.g., AWS NLB)
• Internal ClusterIP service without proxy_protocol

Special notes for your reviewer:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• PR is based off the current tip of the main branch.
• Changes are documented under the "Unreleased" header in CHANGELOG.md
• New or modified sections of values.yaml are documented in the README.md
• Commits follow the Kong commit message guidelines

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[tao12345666333]

I'm concerned about the length here; let me double-check the details.

[tao12345666333]

The final Service name rendered by kong.service is

charts/charts/kong/templates/_helpers.tpl

Lines 172 to 176 in f0dfb5f

	{{- define "kong.service" -}}
	apiVersion: v1
	kind: Service
	metadata:
	name: {{ .nameOverride | default (printf "%s-%s" .fullName .serviceName) }}

where .fullName itself is already {{ .Release.Name }}-{{ .Chart.Name }}. Kubernetes limits Service names to 63 characters, so a long release name combined with a long $name key could exceed this limit.

The chart already applies trunc 63 | trimSuffix "-" in similar places, for example

charts/charts/kong/templates/_helpers.tpl

Line 21 in f0dfb5f

{{- default (printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-") .Values.fullnameOverride -}}

I think we should do the same here. Something like:

{{- $_ := set $serviceConfig "serviceName" (printf "proxy-%s" $name | trunc 63 | trimSuffix "-") }}

[tao12345666333]

additionalProxies streams are added to the deployment container ports, but are not included in KONG_STREAM_LISTEN here. This means Kong won't actually listen on those stream ports even though the container exposes them.

Should add something similar to what was done for KONG_PROXY_LISTEN above:

  {{- range $name, $svcConfig := .Values.additionalProxies -}}
    {{- if $svcConfig.enabled -}}
      {{- $additionalStream := (include "kong.streamListen" $svcConfig) -}}
      {{- if (not (eq $additionalStream "")) -}}
        {{- $streamStrings = (append $streamStrings $additionalStream) -}}
      {{- end -}}
    {{- end -}}
  {{- end -}}