Describe the bug

It's impossible to select a month or a year with the keyboard if the datepicker is a "month picker" or a "year picker".
This is a regression from PrimeNG v17 where it worked in the Calendar.

Pull Request Link

No response

Reason for not contributing a PR

• Lack of time
• Unsure how to implement the fix/feature
• Difficulty understanding the codebase
• Other

Other Reason

No response

Reproducer

https://primeng.org/datepicker

Environment

https://primeng.org/datepicker

Angular version

Whatever https://primeng.org uses

PrimeNG version

v19

Node version

No response

Browser(s)

Firefox and Chrome

Steps to reproduce the behavior

1. Visit https://primeng.org/datepicker#monthpicker or https://primeng.org/datepicker#yearpicker.
2. Using the keyboard, open the datepicker and navigate into it.
3. Try to select a month or a year using the keyboard. It doesn't work because the focus is in the header and no key combination allows the user to focus the months or years.

This is also reproducible if you start with a normal datepicker, for example the one in https://primeng.org/datepicker#basic, then navigate to the header and select either the month or the year heading.

Expected behavior

It must be possible to select a month or a year using the keyboard alone. This is an important accessibility feature.
See https://v17.primeng.org/calendar#monthpicker where pressing tab multiple times makes it possible to actually select a month.