Add an option to "pin date on top" for timeline view (and folder view as well)

[AiroPi]

Is your feature request related to a problem? Please describe.
When we are looking for a specific date, it can be difficult to find the good day just by scrolling.

Describe the solution you'd like
A simple solution that would simplify this task a lot is to always keep the date of the photos we are looking at at the top of the screen.

So even when we are in the middle of a lot of photos of the same day, we know date day these pictures have been picked up.

For example, if we are looking for a photo taken on may 26th, with use the scrollbar to go to the middle of may. If there is a lot of photos on may 20th, we only see these photos, with no date informations. So we don't know if we should go up or down.

We a date always pinned on top, this would be easier.

This is something Immich do (take a look at the demo), and Google photo iirc. (can't test I have deleted all my photos from GP)

[pulsejet]