Split and relocate Data Visualization page

Background/Motivation
Data Visualization ( https://doc.nuxeo.com/nxdoc/data-visualization/ ) is now under Web UI on docs.
The content is more about the services available for data visualisation (elastic search, audit log, etc) and a tutorial on how to create custom dashboards.

This is related to nuxeo elements but not exclusive and therefor could live outside it on a more proper place (with links also to nuxeo elements docs)

Goals

• Take out the https://doc.nuxeo.com/nxdoc/data-visualization/#building-custom-dashboards to a page of its one to be placed in https://doc.nuxeo.com/nxdoc/transversal-how-tos/
• Change the https://doc.nuxeo.com/nxdoc/data-visualization/#data-visualization-elements section to reference the Nuxeo Elements page /nxdoc/nuxeo-elements/ (with the correct anchor) as more detailed information will be there (take out the repo and web components links currently there)
• Relocate what is left of the page to https://doc.nuxeo.com/nxdoc/additional-services/