Refactor LDAP variable schema to use top-level constant LDAP and nested ALL-CAPS keys.

- Converted group_vars/all/13_ldap.yml from lower-case to ALL-CAPS nested keys.
- Updated all roles, tasks, templates, and filter_plugins to reference LDAP.* instead of ldap.*.
- Fixed Keycloak JSON templates to properly quote Jinja variables.
- Adjusted svc-db-openldap filter plugins and unit tests to handle new LDAP structure.
- Updated integration test to only check uniqueness of TOP-LEVEL ALL-CAPS constants, ignoring nested keys.

See: https://chatgpt.com/share/68b01017-efe0-800f-a508-7d7e2f1c8c8d

roles/web-app-bigbluebutton/templates/env.j2

@@ -170,21 +170,21 @@ OAUTH2_REDIRECT=
 #   LDAP_SERVER=ldap.example.com
 #   LDAP_PORT=389
 #   LDAP_METHOD=plain
-#   LDAP_UID={{ ldap.user.attributes.id }}
+#   LDAP_UID={{ LDAP.USER.ATTRIBUTES.ID }}
 #   LDAP_BASE=dc=example,dc=com
 #   LDAP_AUTH=simple
 #   LDAP_BIND_DN=cn=admin,dc=example,dc=com
 #   LDAP_PASSWORD=password
 #   LDAP_ROLE_FIELD=ou
 #   LDAP_FILTER=(&(attr1=value1)(attr2=value2))
-LDAP_SERVER="{{ ldap.server.domain }}"
-LDAP_PORT="{{ ldap.server.port }}"
+LDAP_SERVER="{{ LDAP.SERVER.DOMAIN }}"
+LDAP_PORT="{{ LDAP.SERVER.PORT }}"
 LDAP_METHOD=
-LDAP_UID={{ ldap.user.attributes.id }}
-LDAP_BASE="{{ ldap.dn.root }}"
-LDAP_BIND_DN="{{ ldap.dn.administrator.data }}"
+LDAP_UID={{ LDAP.USER.ATTRIBUTES.ID }}
+LDAP_BASE="{{ LDAP.DN.ROOT }}"
+LDAP_BIND_DN="{{ LDAP.DN.ADMINISTRATOR.DATA }}"
 LDAP_AUTH=password
-LDAP_PASSWORD="{{ ldap.bind_credential }}"
+LDAP_PASSWORD="{{ LDAP.BIND_CREDENTIAL }}"
 LDAP_ROLE_FIELD=
 LDAP_FILTER=
 {% endif %}