Add PoC extending the Job-Scheduler plugin

[AlexRuiz7]

Description

This PR adds a Proof of Concept of the Command Manager plugin, extending the Job Scheduler plugin.

Not functional yet due to the following error:

| Exception in thread "main" java.lang.IllegalArgumentException: Missing plugin [opensearch-job-scheduler], dependency of [wazuh-indexer-command-manager]

The Job Scheduler is correctly added as a dependency of the plugin, however, it seems that the test clusters do not include this plugin. We need to find a way to add it to the test cluster to test and run our plugin. See https://github.com/opensearch-project/geospatial/blob/02e3157738d518a65aa5cf2fec99b58ae7c20f36/build.gradle#L257

Issues Resolved

Closes #65

[f-galland]

Gradle's run job now loads both the command manager and the opensearch-job-scheduler plugin properly:

fede@tyner:~/IdeaProjects/wazuh-indexer-plugins (65-job-scheduler-research +)
$ curl http://localhost:9200/_cat/plugins
integTest-0 opensearch-job-scheduler      2.16.0.0-SNAPSHOT
integTest-0 wazuh-indexer-command-manager 5.0.0.0