Gathering advanced telemetry with visualization configs

[markov00]

We should improve our current telemetry to extract meaningful information about:

• advanced chart configurations (analze precisely the usages of each chart type and feature)
• forecast disruptions of feature deprecations
• remove/reduce unused features and tools
• understand used feature workarounds

To achieve that I think we should get more details about the current chart configurations, rather then just counting the usages of each single feature.
Chart configurations are mostly non-sensible information that can be parsed and used to analyze the general trend and usages of features.

The only possible privacy-sensible parts of a chart configuration are:

• titles and descriptions
• field name/labels
• axis name/labels
• markdown content
• indices names

The gathering method could be done on a demand basis, without any particular schedule.
In the future, this gathering could be done systematically in a scheduled manner to understand the usage trend over time.

[elasticmachine]

Pinging @elastic/kibana-visualizations (Team:Visualizations)