Allow to specify template to use for Dockerfile

[creydr]

• Add template-name option to allow to specify which template to use for the Dockerfile
• Add template for func-util
• Remove symlink-names option again, as this was included in the func-util template directly

/hold until we have feedback from @matejvasek if func-util image works in https://redhat-internal.slack.com/archives/CKR568L8G/p1725614736094379?thread_ts=1725374750.726439&cid=CKR568L8G

[mgencur]

/lgtm

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: creydr, mgencur

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[creydr]

/unhold