Additional Kibana Reporting diagnostics

[tsullivan]

Similar to #676, there are additional diagnostics which would be useful to collect as part of the Kibana Reporting diagnostic stats.

This information is probably found in parts of the Elasticsearch diagnostic bundle, but it would be helpful for the Kibana Platform Engine team to find this information in the Kibana Reporting diagnostics as well.

8.15+

For stack versions 8.15 and higher, it would be useful to collect:

• Check for the existence of the .kibana-reporting template
• Details of the component templates: kibana-reporting@settings and kibana-reporting@custom
• Details of the kibana-reporting ILM policy (or any retention policy that is set on the data stream)
• Whether refreshes are enabled on the data stream
• Check the stack.templates.enabled flag in Elasticsearch

Any version

For any stack version, it would be useful to collect:

• The value of the http.max_content_length setting