[Feature] elasticstack_kibana_slo for synthetic monitors

[niecore]

Is your feature request related to a problem? Please describe. Its currently not possible to configure elasticstack_kibana_slo for synthetic monitors

Describe the resource you would like to have implemented.

Api extract from ui:

But apperently that indicator is not documented in https://www.elastic.co/docs/api/doc/kibana/v8/operation/operation-createsloop#operation-createsloop-body-application-json-elastic-api-version-2023-10-31-indicator

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Additional context Add any other context or screenshots about the feature request here.