Explicitly check if the time window has completed

[IshaanDesai]

Currently, the Micro Manager understands that a time window has converged when the API call requires_reading_checkpoint() is false. However, requires_reading_checkpoint() may return false when the time window has not converged. This could happen, for example, when the Micro Manager is subcycling. To avoid falsely indicating convergence in the Micro Manager, an explicit check using the API command is_time_window_complete() is necessary.

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.

[BenjaminRodenberg]

Looks ok. Before there was clearly something wrong if you are using subcycling.