feat(date-picker): React|WC parity

[warrenmblood]

Closes #19477

Matches date-picker functionality with React version.

• [x] Missing "Default" story
• [x] AI Label gradient is missing
• [x] Move focus to calendar by pressing Tab. See https://github.com/carbon-design-system/carbon/pull/19504
• [x] Esc key should close calendar from input field
• [x] Layer styling is missing in Range With Calendar With Layer
• [x] See parent issue for more.

Changelog

New

• "Default" story
• AI label gradient
• Escape key closes calendar from input field
• Keyboard navigation matches React (press Tab to focus on calendar dropdown)
• Layer styling for Range with Calendar with Layer story
• hideLabel and range properties in cds-date-picker-skeleton matching React version
• Added controls to WC storybook

Changed

• Order and titles of stories matches React
• Calendar dropdown removed from "simple" mode
• Layer names in storybook match React

Removed

• "Playground" story

Testing / Reviewing

• UX and visual review from the design team to ensure consistency
• CI tests should pass
• Ensure functionality matches React version (keyboard nav, simple/single/range modes)

PR Checklist

As the author of this PR, before marking ready for review, confirm you:

• [x] Reviewed every line of the diff
• [x] Updated documentation and storybook examples
• [ ] ~Wrote passing tests that cover this change~
• [x] Addressed any impact on accessibility (a11y)
• [x] Tested for cross-browser consistency
• [x] Validated that this code is ready for review and status checks should pass

More details can be found in the pull request guide

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 84.80%. Comparing base (33dde11) to head (de19440). Report is 22 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #19668   +/-   ##
=======================================
  Coverage   84.80%   84.80%           
=======================================
  Files         369      369           
  Lines       14711    14711           
  Branches     4854     4821   -33     
=======================================
  Hits        12475    12475           
  Misses       2087     2087           
  Partials      149      149           

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