(cherry picked from commit a54a784168c023d1f95c2c1ba0cd97659ffbd08c)

# Conflicts:
#	core/admin/Dockerfile
#	core/dovecot/Dockerfile
#	core/nginx/Dockerfile
#	core/none/Dockerfile
#	core/postfix/Dockerfile
#	optional/clamav/Dockerfile
#	optional/fetchmail/Dockerfile
#	optional/radicale/Dockerfile
#	optional/unbound/Dockerfile
#	setup/Dockerfile

I suggest using the dovecot-fts-xapian package from the alpine repository (newer) instead of compiling an older version from source:
see https://pkgs.alpinelinux.org/package/edge/community/x86/dovecot-fts-xapian

- Moved run to bottom of Dockerfile to allow using unmodified / cached states.
- Simplified bash code in deploy.sh.
- Improved the large bash one-liner in CI.yml. It could not handle >9 for 1.x.

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.

Install py3-multidict from repository before installing socrate to avoid the need of gcc during build

Which is still unreleased, but serves as a placeholder here.

It turns out we were all blind and admin *does* use MailuStart

This reverts commit c787e4bd.

This fix https://github.com/Mailu/Mailu/issues/918

Bash shell is used by default in Kubernetes' dashboard console, which is very
useful for admins.

This fixes #776.
Recursion is not needed, as the permissions will only need to be set on the first invocation.