[Enhancement] Break up retention in Stats by card maturity and show retention for longer periods also

Retention for learning cards and young cards can’t be compared with the retention for mature cards. So, it makes sense to show separate retention for learning cards, young cards and mature cards.

Also, currently, Anki shows only the retention for the past day. But, it would be better if the retention for the past week, the past month, the past 3 months and the past year is also shown. This way, the user can how their retention is changing over time. This is especially useful if the user changes some settings related to the scheduler.

Both of the above feature requests are inspired from the True Retention by Card Maturity add-on.