Add option to query dependency map data for node graph panel

[jangaraj]

It looks like all UQL queries are fired against query_timeseries endpoint. I would like to query also dependency_map endpoint and result use with node graph panel. It looks like a dependency_map endpoint provides data structure similar to structure required by node graph panel (nodes, edges), so only minimal transformation will be required and then also dependency map can be visualised in the Grafana.

I would recommend to mimic Dynatrace query editor UI:

For example:

Query builder (nice clickable UI to build UQL query) is nice to have, but that can be another feature request. I'm happy to write my queries manually.