Purpose of "Reschedule" revlogs

Whenever you use Anki's built in re-scheduler it adds an extra "Reschedule" review to the review history, increasing the collection size. The helper add-on does not do this while rescheduling.

Anki:
https://github.com/ankitects/anki-core-i18n/blob/1eb7a27f80029b7ac1c6f107ee67d8ca3606db24/core/templates/deck-config.ftl#L453-L458

> Use this option sparingly, as it will add a review entry to each of your cards, and
increase the size of your collection.

Helper:
https://github.com/open-spaced-repetition/fsrs4anki-helper#overview

> When you update the parameters or desired retention of FSRS. Rescheduling with the Helper does not add to the size of your collection, unlike Anki's built-in "Reschedule cards on change."

I'm not sure what purpose the reschedule revlogs serve. I'd assume it's to inform the users as to why the due date is different to what is stated int heir revlog history. In this case maybe it would be best just to keep the latest reschedule entry?

It might also be a good idea to expose a method of calling the re-scheduler to python so that the helper add-on can make use of it. Although personally I prefer the helper add-ons method of rescheduling without the revlog; so it might be better to leave them separate and give users the option.

Read core/templates/deck-config.ftl lines 453-458 and the FSRS helper overview first, then trace the built-in re-scheduler and its revlog handling. Done requires a maintainer decision on the purpose and retention of “Reschedule” entries and whether Python access to the re-scheduler is needed, followed by corresponding implementation or documentation.

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