datepicker

Users may want to change the first day of the week.

• Add a new prop weekStartsOn: 0 | 1 | 2 | 3 | 4 | 5 | 6 (default: 0) to be passed to the startOfWeek implementations
• Check if other parts should change according to this prop
• Add test
• Add documentation

Describe the bug
Currently @duetds/date-picker does not work with Rollup (or I didn't get it to).
The problem appears to be a dynamic import statement with a template string:

return import(`./${bundleId}.entry.js${""}`);

Rollup seems to ignore these imports: "Dynamic imports on runtime are ignored by Rollup #2463"

**To

Hi there, thanks for the great work on this library!

Can I just check what is the best way to ensuring the calendar popup is hidden when tabbing out of an input within a <DatePicker /> example?

Currently it's remaining open when I'm tabbing from one form item to another.

Thanks!