feat(encryption): Make cilium encryption configuration manageable via NetworkConfig

[Meecr0b]

How to categorize this PR?
/area networking
/kind enhancement

What this PR does / why we need it:
Ciliums encryption configuration is already part of the internal config helm chart, but is not configurable via NetworkConfig.

Release note:

feature user
enable cilium encryption configuration via NetworkConfig

[CLAassistant]

All committers have signed the CLA.

[gardener-prow]

Hi @Meecr0b. Thanks for your PR.

I'm waiting for a gardener member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[gardener-robot]

@Meecr0b Thank you for your contribution.

[gardener-robot-ci-1]

Thank you @Meecr0b for your contribution. Before I can start building your PR, a member of the organization must set the required label(s) {'reviewed/ok-to-test'}. Once started, you can check the build status in the PR checks section below.