[Docs] Add content how to configure LDAP and role mapping

https://access.redhat.com/documentation/en-us/red_hat_data_grid/8.3/html/data_grid_server_guide/security-realms#ldap-security-realms_security-realms

Expand the docs and add information on how to run local LDAP server and set up TLS and OAuth2

Add LDAP config file example for both cases

<ldap-realm name="ldap" url="ldaps://${org.infinispan.test.host.address}" principal="uid=admin,ou=People,dc=infinispan,dc=org" credential="strongPassword" client-ssl-context="realm-with-truststore">

LDAP configuration used to generate the "LDAP Realm" (documentation)

reported by @alopezme@redhat.com