[8.x] Adds cluster, graph and ILM API example requests and responses

[szabosteve]

Overview

This PR backports the following changes to the 8.x branch:

• Adds graph and ILM API example requests and responses Adds graph and ILM API example requests and responses #2900
• Adds cluster API example requests and responses #2870

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
graph.explore	🟢	4/4	4/4
ilm.delete_lifecycle	🟢	2/2	2/2
ilm.explain_lifecycle	🟢	5/5	5/5
ilm.get_lifecycle	🟢	8/8	8/8
ilm.get_status	🟢	4/4	4/4
ilm.migrate_to_data_tiers	⚪	Missing test	Missing test
ilm.move_to_step	⚪	Missing test	Missing test
ilm.put_lifecycle	🟢	6/6	6/6
ilm.remove_policy	🟢	5/5	5/5
ilm.start	⚪	Missing test	Missing test
ilm.stop	🟢	4/4	4/4

You can validate these APIs yourself by using the make validate target.

[lcawl]

Works for me, thanks!

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
cluster.allocation_explain	🟢	4/4	4/4
cluster.health	🟢	153/153	153/153
cluster.put_settings	🟢	58/58	57/57
cluster.reroute	🟢	6/6	5/5
graph.explore	🟢	4/4	4/4
ilm.delete_lifecycle	🟢	2/2	2/2
ilm.explain_lifecycle	🟢	5/5	5/5
ilm.get_lifecycle	🟢	8/8	8/8
ilm.get_status	🟢	4/4	4/4
ilm.migrate_to_data_tiers	⚪	Missing test	Missing test
ilm.move_to_step	⚪	Missing test	Missing test
ilm.put_lifecycle	🟢	6/6	6/6
ilm.remove_policy	🟢	5/5	5/5
ilm.start	⚪	Missing test	Missing test
ilm.stop	🟢	4/4	4/4
nodes.info	🔴	113/113	1/113
nodes.reload_secure_settings	🟢	2/2	2/2
tasks.get	🟢	10/10	10/10

You can validate these APIs yourself by using the make validate target.