QGIS add node screen shows all data tables

[visr]

When creating a new node in QGIS, since #1756 we see all possibly related tables appear in the window.
Since almost all tables are related to Node, this is a long list of tables.
Ideally a user would choose a node type, and only the tables related to that node type would appear, e.g. for Pump, show Pump / static.

Also the table view would probably be easier to understand for users than the form view, by default.