Declarative installation of some Jellyfin plugins

[ibizaman]

This would be at least super useful to keep up to date the LDAP and OID plugins. As can be seen from #262, that can introduce issues if not kept up to date.

Second, without installing those plugins one can’t use the SSO or LDAP plugin without installing them manually and it’s not explicit at all. When clicking on the sign in with Authelia button, you just get a blank page.