fix(config-syncer): b64enc $serverKey and $serverCrt

[jjangga0214]

Hi!

I believe in most cases people provide certificates by --set-file.

helm install config-syncer \
  --set-file apiserver.servingCerts.serverCrt=config-syncer.crt \
  --set-file apiserver.servingCerts.serverKey=config-syncer.key \
  ./config-syncer

The files(e.g. config-syncer.crt, config-syncer.key) are raw certificates(not pre-encoded) in general.
So the chart should b64enc by itself.

Whether to consider this a breaking change or a major feature or a minor patch is up to you,
though I think it's not actually a breaking change but a patch, because this behavior is highly expected conventionally.

Thanks :)

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