feat: show split data during fall DST transition in daily heatmap

[Flix6x]

This PR masks overlapping data during a DST transition (commonly on 1 day during fall) and then shows it split up vertically in a separate layer.

A small horizontal white bar (with height probably equal to 1/25th of the row height) is still visible, but it's a bit of a pain to get rid of.

[Flix6x]

Update without the white bar:

[victorgarcia98]

Looks good!

The only thing is that somehow we should indicate which block (top and bottom) belongs to what timezone (UTC+1 or UTC+2, in general, $timezone \pm 1$ ).

Aside, maybe we should also warn that the user is visualizing a period that contains a change of hour.

[victorgarcia98]

It looks great!

Some comments and test that I run:

• The chart looks a bit broken when there's no data in the selected period:

• The message Please note that the sensor data you are viewing includes a daylight saving time (DST) transition. appears in both types of charts. I like this though as it reminds you that you could see some "artifacts".

• Both messages look good, maybe the space it too big. Also, I would prefer to see the offset in hours, although it's good like it is.