Skip CI jobs for draft PRs

[lenaploetzke]

Feature request

We agreed to create draft PRs early in order to get early feedback and promote exchange with the other developers. However, the CI is currently triggered with every commit in draft PRs. It is not possible not to trigger the CI for Draft PRs at all, but we could skip the majority of the jobs (see also https://github.com/orgs/community/discussions/102838).
We just have to add if: github.event.pull_request.draft == false to the jobs that should not run in the case of draft PRs.

Is your feature request related to a problem? Please describe.
The CI runs for every commit in draft PRs

Describe alternatives you've considered
Use [ci skip] in draft PRs more frequently.

Estimated priority
"Priority: medium" Should be solved within half a year

[sandro-elsweijer]

• We discussed that the CMake CI should be skipped in draft PRs unless the commit message indicates otherwise (like including a [run ci]). This can easily be achieved via @lenaploetzke's proposed solution and the addition of the parsing of the commit message for s specific substring.
• The spell and indentation check should run as usual.
• The tarball test should only be run in the nightly and the merge queue.
• The tests in the merge queue should run the full test suite (without less tests)
• Then all tests (including spell and indent) after a merge into main can be deactivated because they ran already in the merge queue.

[Davknapp]

• The tarball test should only be run in the nightly and the merge queue.

This is probably not possible in the current setup.
A merge queue runs on top of the branch protection. There is not a seperate rule-set for the merge queue.
If we want to ensure that the tarball can be constructed properly we should put this test in our branch protection (and I think it is a good idea). But this means that it has to run on every PR.