Fix timezone due date picker

What does this MR do?

Closes a Community Contribution MR !7422 (closed) which needed to be rebased and have some linting errors fixed.

There is a date inconsistency when we instantiate the Date object passing the date as string and we should avoid it as the MDN recommends - https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Date

This inconsistency is the reason for the bug described here: https://gitlab.com/gitlab-org/gitlab-ce/issues/24253.

Below, we can see different results according to the use of the string. For example, with dashes, the browser (Chrome) ignores the time zone which results in a wrong date. In order to solve this, we can instantiate the Date object passing the year, month (zeroBased) and day as integer params.

Closes #24253 (closed)

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #24253 (closed)