feat: Add button to return to previous position after clicking on "You have new notes"

What feature would you like implemented?

Show a button or convert current timeline button (like on tumblr mobile app) to a button that returns to the previous position after pressing the "You have new notes" button that goes to the top of the timeline.

Why should we add this feature?

This is useful for checking quickly the new notes when you are deep reading your timeline and not losing the position you where previously

Version v2024.2.0-beta.12

Instance lethallava.land

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changed the description

implementing this currently could be difficult due to upstream misskey's behavior of unloading all off-screen posts when scrolled to the very top as opposed to doing proper virtual scrolling

yeah, even after !495 (merged) it's still going to be a pain

added enhancement label