Add an LDAP server example

[nwneisen]

We currently have a dev setup that makes it easy to run an LDAP server for testing against: https://github.com/MirantisContainers/mke/blob/main/docs/dev/dex-LDAP-server.md

This should be added to our public docs so that customers can just as easily run an LDAP server for testing against

This will include the

• docker-compose.yml code for the LDAP server
• The ldif file that gets copied into the container
• The MKE4 config
• The docker compose command

[KoryKessel-Mirantis]

Done dooby doo done done.