[Feature] Backward compatibility for older version of Synthetic Monitor

[doom160]

Is your feature request related to a problem? Please describe.
Currently I am running older version of Elastic cloud 8.12.2. Currently Im automating the synthetic monitor creation via mastercard rest_api via /internal/synthetics/service/monitors. Noticed that now there are formal support to deploy synthetic monitor and i will want to do so.

Tried and failed with " Not Found%!(EXTRA string=Not Found)" and suspect the code supports only new endpoint which i have checked that it was only available for 8.14 onwards. Since synthetic monitor feature is available for sometime back, will it be possible for backward compatibility for this provider?

https://github.com/biscout42/terraform-provider-elasticstack/blob/28934ed06a28dc1b853815c441ed5ec0dc96e9cf/libs/go-kibana-rest/kbapi/api.kibana_synthetics.go#L15

Describe the resource you would like to have implemented.
elasticstack_kibana_synthetics_monitor

Describe the solution you'd like
To have a check on user's Kibana version, if its <8.14, call the old endpoint, else the current endpoint. There are chances of older ES might have fields mapping changes, i hope its not significant! based on my testing, only max_redirects has changes

Describe alternatives you've considered

• Stick to my current rest_api way
• Probably also good to let users know that it only support certain version of ES onwards if there are no plans to support backward compatibility

Additional context
Of course i could have just upgrade my Elasticsearch but my organization is not ready to adopt new version yet.