[bitnami/external-dns] Add exoscale external-dns values

[jonesbusy]

Description of the change

Add exoscale external dns values supported by kubernetes-sigs/external-dns#625

Benefits

Support for exoscale cloud provider

Possible drawbacks

Applicable issues

• fixes [bitnami/external-dns] Support for Exoscale provider #15734

Additional information

Checklist

• Chart version bumped in Chart.yaml according to semver. This is not necessary when the changes only affect README.md files.
• Variables are documented in the values.yaml and added to the README.md using readme-generator-for-helm
• Title of the pull request follows this pattern [bitnami/<name_of_the_chart>] Descriptive title
• All commits signed off and in agreement of Developer Certificate of Origin (DCO)

[jonesbusy]

Test done on SKS cluster and Exoscale DNS

helm upgrade --install --namespace external-dns --version 6.16.0 --set dryRun=false --set logLevel=debug  --set provider=exoscale --set exoscale.apiKey=$EXOSCALE_API_KEY --set exoscale.apiToken=$EXOSCALE_API_SECRET external-dns external-dns-6.16.0.tgz
kubectl run nginx --image=nginx --port=80
kubectl expose pod nginx --port=80 --target-port=80 --type=LoadBalancer
kubectl annotate service nginx "external-dns.alpha.kubernetes.io/hostname=nginx.<zone>."

[jonesbusy]

Rebased to resolve conflict on chart version

[Mauraza]

Hi @jonesbusy,

Thanks for the contribution! LGTM!