Currently we are not able to offer our users a FTS experience after the
demise of lucene due to unfixed coredumps with musl/alpine.
We now add lucene, the only remaining maintained small/lean FTS plugin
for dovecot. It is quite simple to add to our stack: A two-stage docker
build is used to compile the fts plugin in the first stage, and copy
over only the resulting plugin-artifact to the second stage, which is
our usual dovecot container. Configuration is also minimal.