Add concept of Periodic Maintenance Task

[gnthibault]

We have identifier multiple task that should be run with a given periodicity and/or depending on some run statistics.
IE:

• Build dark and offset for all cameras periodically
• Re-calibrate mount model, (ie wipe out + select a set of star and perform astrometry + sync on them)
• Re-update phd2 calibration on a star close to equator
• Perform polar align test periodically

We should implement a proper way of scheduling those complex tasks, that involve potentially a specific scheduler, and potentially keep track of pointing statistics and guiding statistics specifically.

[gnthibault]

Info on client for calibration: https://www.indilib.org/api/md_libs_indibase_alignment_alignment_white_paper.html
PDF version:
Instrument Neutral Distributed Interface INDI_ INDI Alignment Subsystem.pdf