helm: Add extraConfig in configmap template

[michi-covalent]

This allows users to provide additional fields in the configmap without
having them explicitly listed in the template. For example, you can do:

% cat my-config.yaml
extraConfig:
  my-config-a: "1234"
  my-config-b: |-
    test 1
    test 2
    test 3
% helm install ./cilium -n kube-system -f ./my-config.yaml

to add my-config-a and my-config-b to cilium-config. This could be
useful in case the template is missing some fields.

Ref: #13317

Signed-off-by: Michi Mutsuzaki michi@isovalent.com

[sayboras]

👍 to have similar feature as per 1.8

[michi-covalent]

thanks @sayboras i forgot to add context here. this is "forward porting" #13317 i made the change in v1.8 branch without making the change in the master branch first as there was an ongoing helm chart refactoring around that time.

[nathanjsweet]

test-me-please

[gandro]

Added the ready-to-merge label as I don't think this needs to run through full CI, as it does not affect the output of the Helm rendering with the new value is not used.