dsconf / dscreate should be able to handle lmdb parameters

[progier389]

Issue Description
lmdb specific parameters should be visible in dsconf

Package Version and Platform:

• Platform: Fedora
• Package and version: main
• Browser [e.g. chrome, safari]

Steps to Reproduce
Steps to reproduce the behavior:

1. Configure an instance with lmdb
2. Run dsconf supplier1 backend config set --help

Expected results
Should see the lmdb specific parameters like:

• nsslapd-mdb-max-size
• nsslapd-mdb-max-readers
• nsslapd-mdb-max-dbs

Additional context
dscreate create-template should also propose the nsslapd-mdb-max-size as it is a critical parameter
dscreate interactive should ask for

• the bdb/mdb mode
• the mdb max size if in mdb mode

[progier389]

dscreate needs to be able to handle these parameters but we cannot change these value afterwards
without removing the whole db and recreating it ( lmdb limitation) so I do not think that dsconf should be changed.
we will have to describe how to change
see also issue #5844 that is related.

[Firstyear]

Thinking more about this, I think that we shouldn't have a default size. We should always force the admin to select a size here. That way they are always aware of the choice they need to make and don't have a "surprise you're out of DB space" event in the future.

We also need to carefully consider how this will work with upgrades in the future too - if we want them to be a manual or hands-off process.

[progier389]

Found a regression with dscreate create-template when creating first instance on a newly installed host
(Get a warning about not existing directory in the middle of the template ! )
Opening a new PR

[progier389]

Regression fixed by PR #5950