Data mapping: add the data preview tables for mapped data, similar to Darwin Core

[ahahn-gbif]

For DwC resources, data mappings contain an "eye" symbol, giving access to a data preview; see e.g. the "Edit" view of https://ipt.gbif.org/manage/resource.do?r=18s-wo-kingdom-phylum:

These previews are very helpful for quick checking and feedback on data mappings, and would be helpful also for other resources like CamtrapDP data (e.g. https://ipt3.gbif-uat.org/manage/resource?r=more_camtrap) where they are currently not available.

[mike-podolskiy90]

Thanks!

[mike-podolskiy90]

Some more work required here to implement, will be included in one of the next releases