mail/dovecot-fts-flatcurve: NEW Port

This is a Dovecot FTS plugin to enable message indexing using the Xapian
Open Source Search Engine Library.

The plugin relies on Dovecot to do the necessary stemming.
It is intended to act as a simple interface to the Xapian
storage/search query functionality.

This driver supports match scoring and substring matches (on by
default), which means it is RFC 3501 (IMAP4rev1) compliant.
This driver does not support fuzzy searches.

WWW: https://github.com/slusarz/dovecot-fts-flatcurve

PR: 261766