Datepicker header a bit confusing

[jancborchardt]

You want to change to the next month, which button do you click?

It’s confusing. There is a very simple way of switching the years by clicking on the year already.

So we can simplify to a single forward arrow and backward arrow which would switch the months only.

(Also the vertical alignment is off a bit.)

cc @georgehrke

[georgehrke]

cc @skjnldsv

[georgehrke]

I'm not sure how far we can customise it. We are still using version 2 of vue2-datepicker and there is a major update to version 3 available. Let's update to 3 first and afterwards see what we can do.