Backport text command - Set labels to PRs

[EduPonz]

Hi everyone,

We have this workflow were we develop against main and backport things to older supported versions using your this amazing tool. Our CI infrastructure is prepared to do different actions depending on the labels set on a PR when it's opened (in some cases we can avoid running tests, etc). When backporting PR which have these kinds of labels using the backport text command on a comment, we would like the ability to somehow keep the labels in the backport PRs openned by Mergify or even specify which labels should be added to the new PRs. I've seen that this is already possible with the Github action, so maybe adding this feature to the text command is not that difficult.

[jd]

Hi @EduPonz !

1. You could set labels to always add by using the default section of the configuration, but I doubt this would be useful.

2. You could leverage a GHA to copy the label from the original PR. We have something similar for copying labels in the merge queue: https://github.com/Mergifyio/gha-mergify-merge-queue-labels-copier