Allow to choose whether the inserted ticket reference “resolves” the ticket

[ejpcmac]

Rationale

Both GitHub and GitLab allow to reference issues in commits, but also auto-close the related issue when the commit is merged, thanks to some keywords.

Currently, the commit template allows to format arbitrarily the issue number, so one could write Refs: #{{ ticket }} to only create a reference, and something like Closes #{{ ticket }}. to trigger an auto-close. However, this template applies to all commits, so we cannot choose which of the wordings should be used on a per-commit basis.

Concept

Ask the user whether the current commit closes the ticket / issue or just refers to it.