Fix the adaptivity data check

[fsimonis]

This PR changes the error message when the initialize() function of the Micro Simulations doesn't exactly return the data expected for adaptivity.

It now only errors when data is missing.
Having extra data leads to a warning.

Closes #260

Checklist:

• I made sure that the CI passed before I ask for a review.
• I added a summary of the changes (compared to the last release) in the CHANGELOG.md.
• If necessary, I made changes to the documentation and/or added new content.
• I will remember to squash-and-merge, providing a useful summary of the changes of this PR.