Add support for AD year notation in Danish locale

[coderabbitai]

While the BC notation ('f.kr.') is correctly implemented in 'da-dk/date_time.json', the format is missing explicit support for AD years ('e.kr.' in Danish).

References:

• Pull Request feat: nice_xx #1: feat: nice_xx #1
• Comment: feat: nice_xx #1 (comment)
  Requester: @JarbasAl