Add lookup modules for activations

[robin-checkmk]

Pull request type

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Check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
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• Documentation content changes
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What is the current behavior?

Describe the current behavior that you are modifying, or link to a relevant issue.

There are no lookup plugins for activations.

What is the new behavior?

Describe the behavior or changes that are being added by this PR.

There are lookup plugins for activations. One to list all running activations and one to look up a specific activation.

Other information

Any other information that is important to this PR, e.g screenshots of how the component looks before and after the change.

[robin-checkmk]

While this is generally ready for review, the code needs a thorough going through and the integration tests are rather limited and might need an additional angle. Please review diligently.

[lgetwan]

The actual code looks fine.
I just have an improvement suggestion for the integration tests.

[lgetwan]

Looks good to me, now!