[8.x] Add simulate.ingest specification (#3400)

[lcawl]

Backport

This will backport the following commits from main to 8.x:

• Add simulate.ingest specification (#3400)

Questions ?

Please refer to the Backport tool documentation

[github-actions]

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

API	Status	Request	Response
ingest.delete_geoip_database	🟢	1/1	1/1
ingest.delete_ip_location_database	🟢	1/1	1/1
ingest.delete_pipeline	🟢	15/15	15/15
ingest.geo_ip_stats	🟢	1/1	1/1
ingest.get_geoip_database	🟢	6/6	6/6
ingest.get_ip_location_database	🟢	7/7	7/7
ingest.get_pipeline	🟢	22/22	22/22
ingest.processor_grok	🟢	1/1	1/1
ingest.put_geoip_database	🟢	3/3	3/3
ingest.put_ip_location_database	🟢	4/4	4/4
ingest.put_pipeline	🟢	60/60	60/60
ingest.simulate	🟢	10/10	10/10
simulate.ingest	🔴	11/12	12/12

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