Add possibility to configure custom dnsConfig on the Nextcloud pod

[nliechti]

Description of the change

The change allowes to configure dnsOptions on all nextcloud pods

Benefits

In some Clusters this option needs to be set. For example k3s clusters can have problems running alpine images.

Possible drawbacks

None

Applicable issues

Additional information

Checklist

• I have read the CONTRIBUTING.md doc.
• DCO has been signed off on the commit.
• Chart version bumped in Chart.yaml according to semver.
• (optional) Parameters are documented in the README.md

[jessebot]

Awesome PR, @nliechti, thank you! Could you please bump the version in charts/nextcloud/Chart.yaml? Since this is a minor change that adds new functionality without impacting existing functionality, it's fine to use a minor version update, so 5.2.2 becomes 5.3.0. Then, I can approve the workflow and when the checks pass, we can get this merged :)