Improve CI to a more finegrained CI

[Davknapp]

Closes #1425

For a detailed description, please have a look at the Issue. We decided to optimize our CI, this branch implements the decision that we made.

TODOS:

• 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

All these boxes must be checked by the reviewers before merging the pull request:

As a reviewer please read through all the code lines and make sure that the code is fully understood, bug free, well-documented and well-structured.

General

• The reviewer executed the new code features at least once and checked the results manually

• The code follows the t8code coding guidelines

• New source/header files are properly added to the Makefiles

• The code is well documented

• All function declarations, structs/classes and their members have a proper doxygen documentation

• All new algorithms and data structures are sufficiently optimal in terms of memory and runtime (If this should be merged, but there is still potential for optimization, create a new issue)

Tests

• The code is covered in an existing or new test case using Google Test

Github action

• The code compiles without warning in debugging and release mode, with and without MPI (this should be executed automatically in a github action)

• All tests pass (in various configurations, this should be executed automatically in a github action)

  If the Pull request introduces code that is not covered by the github action (for example coupling with a new library):

  • Should this use case be added to the github action?
  • If not, does the specific use case compile and all tests pass (check manually)

Scripts and Wiki

• If a new directory with source-files is added, it must be covered by the script/find_all_source_files.scp to check the indentation of these files.
• If this PR introduces a new feature, it must be covered in an example/tutorial and a Wiki article.

License

• The author added a BSD statement to doc/ (or already has one)

Tag Label

• The author added the patch/minor/major label in accordance to semantic versioning.

[Davknapp]

It is not possible to run the tarball action only in the nightly build and in the merge queue, as long as it is part of the branch protection rule for main.
We could hack it, such that it always returns true, but only really runs when the output of the fine_grained_trigger workflow is set to true, but that way we will easily miss it when something breaks. So we should not do it in my opinion and rather take the cost of this workflow to always run.

[sandro-elsweijer]

Only minor comments