Support /import endpoint

[safaci2000]

This was triggered from a conversation I had with grafana folks:

If you want to share dashboards among different grafana instances then the endpoint to use is the /import one. This endpoint tries to create all the library panels that do not already exist in the new instance. If a library panel with the same UID already exists in the new instance then it will ignore it. This was implemented as part of grafana/grafana#39214 work. For more details please check the implementation there.

It seems like there is a use case where we should have the /import endpoint in the SDK.