Introduced input trigger for date-picker

[msereniti]

Description

Introduced input trigger for date-picker. In general it works but there are still some doubts. Also I need to update documentation, handle button trigger deprecation in better way and add tests.

Old button trigger is still used by default for backward compatibility. Hope we will replace it in nect major release.

Motivation and Context

Button trigger is inaccessible for blind users and not handy for keyboard only users. My hypothesis is that input trigger will resolve these issues.

How has this been tested?

I have added more vo-tests

Screenshots:

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.

[lsroman]

Lena described all the main points 👌 I think, we need to synchronize with designers about the size and jumps of the font. I also wanted to add that the up and down arrows should work.