Add attention base class

[TillHae]

Description

Adds base class for attention mechanism that all other attention classes inherit from.
This avoids duplications as much as possible.

CC @clessig, @csjfwang

Issue Number

Closes #2130

Is this PR a draft? Mark it as draft.

Checklist before asking for review

• I have performed a self-review of my code
• My changes comply with basic sanity checks:
  • I have fixed formatting issues with ./scripts/actions.sh lint
  • I have run unit tests with ./scripts/actions.sh unit-test
  • I have documented my code and I have updated the docstrings.
  • I have added unit tests, if relevant
• I have tried my changes with data and code:
  • I have run the integration tests with ./scripts/actions.sh integration-test
  • (bigger changes) I have run a full training and I have written in the comment the run_id(s): launch-slurm.py --time 60
  • (bigger changes and experiments) I have shared a hegdedoc in the github issue with all the configurations and runs for this experiments
• I have informed and aligned with people impacted by my change:
  • for config changes: the MatterMost channels and/or a design doc
  • for changes of dependencies: the MatterMost software development channel

[TillHae]

Maybe we should create a separate PR for just ruffing the repository again. The failed cscs/test-single test seems to already fail at creating the environment.

[TillHae]

@csjfwang do you have some time in the upcoming weeks to review it? You can ignore all changes that are not in attention.py. They are just due to linting.

[TillHae]

@clessig is the refactoring of the attention class still needed or do you want to close the issue and PR?

[clessig]

@clessig is the refactoring of the attention class still needed or do you want to close the issue and PR?

Yes, that would still be good

[TillHae]

Here is the UML-diagram showing how the structure was before and is currently:

Here is the UML-diagram showing how the structure would be with this PR: