Create a plugin for custom resource views

[Aklakan]

For a given set of RDFnodes enable:

• determine applicable data shapes (e.g shacl) and view components

on that basis:

• retrieve corresponding triples (e.g. nested property structures)
• present retrieved data using an appropriate vaadin component

[Aklakan]

The system is now in place and working - the central classes being ViewTemplate and ViewFactory in conjunction with ViewManager.

Currently the 'shape' needs to be provided as an entity query which is a sparql-based model for composing sparql syntax elements for specifying a set of entities together with attributes. We should add support for a specification using shacl which is then compiled to an EntityQuery. The compilation code is mostly rewritten in the class NodeSchemaDataFetcher.
NodeSchema is essentially the SPARQL-centric version of a NodeShape - i.e. conditions over a set of triples are expressed in terms of SPARQL expressions which e.g. allows the use of SPARQL functions such as langMatches.