Implement composable (V2) templates in High Level Client

[vkras]

Is your feature request related to a problem? Please describe.
From what I can see, only legacy (deprecated) templates are implemented in the latest version of NEST.

Describe the solution you'd like
I want new component templates and index templates (AKA Templates V2, composable templates) added to NEST.

Describe alternatives you've considered
Low Level client but it requires manual mapping for results

Additional context
Old V1 templates are deprecated and throw warning below:
"Legacy index templates are deprecated in favor of composable templates."

[stevejgordon]

Hi, @vkras. Component template APIs were added in 7.16.0 under the cluster area of the client client.Cluster.GetComponentTemplate for example. Index Template (v2) APIs were indeed missing. I've added these in #6101 and will release them in 7.17.0.

[vkras]

Thank you, it was fast.