Chore: Group auth docker blocks (#54274)

* Move auth docker images to parent folder

* Add README file for auth parent folder

* Add grafana-authnz-team as code owner

* Update `devenv` docs

devenv/docker/blocks/auth/openldap-multiple/ldap-server.Dockerfile

@@ -0,0 +1,30 @@
+# Fork of https://github.com/dinkel/docker-openldap
+
+FROM debian:jessie
+
+LABEL maintainer="Grafana team <hello@grafana.com>"
+
+ENV OPENLDAP_VERSION 2.4.40
+
+RUN apt-get update && \
+    DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends -y \
+        slapd=${OPENLDAP_VERSION}* \
+        ldap-utils && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+RUN mv /etc/ldap /etc/ldap.dist
+
+EXPOSE 389
+
+VOLUME ["/etc/ldap", "/var/lib/ldap"]
+
+COPY ldap-server/modules/ /etc/ldap.dist/modules
+COPY ldap-server/prepopulate/ /etc/ldap.dist/prepopulate
+
+COPY ./entrypoint.sh /entrypoint.sh
+COPY ./prepopulate.sh /prepopulate.sh
+
+ENTRYPOINT ["/entrypoint.sh"]
+
+CMD ["slapd", "-d", "32768", "-u", "openldap", "-g", "openldap"]