Add the Enroll Kibana API (#72207)

This change adds the Enroll Kibana API that enables a Kibana instance to
configure itself to communicate with a secured elasticsearch cluster

docs/java-rest/high-level/security/enroll_kibana.asciidoc

@@ -0,0 +1,47 @@
+--
+:api: kibana-enrollment
+:request: KibanaEnrollmentRequest
+:response: KibanaEnrollmentResponse
+--
+
+[id="{upid}-{api}"]
+=== Enroll Kibana API
+
+Allows a kibana instance to configure itself to communicate with a secured {es} cluster.
+
+include::../execution.asciidoc[]
+
+[id="{upid}-{api}-response"]
+==== Enroll Kibana Response
+
+The returned +{response}+ allows to retrieve information about the
+executed operation as follows:
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests-file}[{api-kibana-response]
+--------------------------------------------------
+<1> The password for the `kibana_system` user
+<2> The CA certificate that has signed the certificate that the cluster uses for TLS on the HTTP layer,
+as a Base64 encoded string of the ASN.1 DER encoding of the certificate.
+
+[id="{upid}-{api}-execute-async"]
+==== Asynchronous Execution
+
+This request can be executed asynchronously using the `security().enrollClientAsync()`
+method:
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests-file}[{api}-execute-async]
+--------------------------------------------------
+
+A typical listener for a `KibanaEnrollmentResponse` looks like:
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests-file}[{api}-execute-listener]
+--------------------------------------------------
+<1> Called when the execution is successfully completed. The response is
+provided as an argument
+<2> Called in case of failure. The raised exception is provided as an argument