Date picker component limited keyboard support

[jeffreychen-eightfold]

The date picker components do not have keyboard support for the next month and next year arrow buttons at the top of the component or other buttons like the Today button. This is desired for accessibility.

Related links
JIRA https://eightfoldai.atlassian.net/browse/ENG-38676
Guidelines https://www.w3.org/WAI/ARIA/apg/example-index/dialog-modal/datepicker-dialog

[dkilgore-eightfold]

Tracking with ENG-41361

[dkilgore-eightfold]

@jeffreychen-eightfold Here are the keyboard shortcuts:

Tab - Places focus on the calendar in the dropdown

Date mode:
Arrow left - Previous day
Arrow right - Next day
Arrow down - Next week
Arrow up - Previous week
Page down - Next month
Page up - previous month
CTRL + Arrow left - Previous year
CTRL + Arrow right - Next year

Week mode:
Arrow left - N/A
Arrow right - N/A
Arrow down - Next week
Arrow up - Previous week
Page down - Next month
Page up - previous month
CTRL + Arrow left - Previous year
CTRL + Arrow right - Next year

Month mode:
Arrow left - Previous month
Arrow right - Next month
Arrow down - Next month row
Arrow up - Previous month row
CTRL + Arrow left - Previous year
CTRL + Arrow right - Next year
Page down - N/A
Page up - N/A

Year mode:
Missing selected style, should map to the same pattern as Decade mode.

Decade mode:
Arrow left - Previous decade
Arrow right - Next decade
Arrow down - Next decade row
Arrow up - Previous decade row
CTRL + Arrow left - Previous century
CTRL + Arrow right - Next century
Page down - N/A
Page up - N/A

So there is a bug in Year mode where the selected style is missing, it should map to the same pattern used by Decade. Will fix this and consider focus on the buttons as well to provide additional A11y functionality.