[enhancement]: IMAP XAPPLEPUSHSERVICE support

[Avamander]

Which feature or improvement would you like to request?

Support for XAPPLEPUSHSERVICE IMAP extension would allow Apple IMAP clients to use native push messages instead of polling (because Apple clients do not use IDLE), which provides a better user experience.

Further references:

• https://docker-mailserver.github.io/docker-mailserver/latest/examples/use-cases/ios-mail-push-support/
• https://github.com/freswa/dovecot-xaps-plugin/blob/197d68e9d0f4f802aff06f90ffd2c1957394a380/xaps-imap-plugin.c#L40-L63
• Feat: Add support for XAPPLEPUSHSERVICE nodemailer/wildduck#711
• https://lists.apache.org/thread/52o1s2wz4joj28bz4cm1cbj4o9j3zm2f
• https://opensource.apple.com/source/dovecot/dovecot-293/

Code of Conduct

• I agree to follow this project's Code of Conduct