feat: Add lifecycle hook

[inerplat]

Add container lifecycle hook to helm chart of code-server deployment

It was tested in my self-hosted k8s cluster:

1. Write custom-values.yaml for helm deploy

   # custom-values.yaml
   replicaCount: 1
   service:
     type: ClusterIP
     port: 8080
   lifecycle:
     enabled: true
     postStart:
       exec:
         command:
           - /bin/bash
           - -c
           - curl -s -L https://<my-script-url> | bash

2. Deploy helm chart with values

   helm upgrade --install code-server . -f custom-values.yaml
   

3. Check deployed manifest by kubectl

   $ kubectl get deploy code-server -o yaml | grep lifecycle -A7 -B0
   
           lifecycle:
             postStart:
               exec:
                 command:
                 - /bin/bash
                 - -c
                 - curl -s -L https://<my-script-url> | bash

Related to #5382

[codecov]

Codecov Report

Merging #5397 (c252510) into main (6b9bb89) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #5397   +/-   ##
=======================================
  Coverage   72.42%   72.42%           
=======================================
  Files          30       30           
  Lines        1672     1672           
  Branches      366      366           
=======================================
  Hits         1211     1211           
  Misses        398      398           
  Partials       63       63           

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[jsjoeio]

@bpmct @Matthew-Beckett do you mind helping us review this?

[bpmct]

LGTM