Implement Graph printing in Mermaid for AST subtree and parent

[konradweiss]

Currently we have the printDFG function in the Mermaid printer. An implementation for printEOG exists but is commented out. In the long run we should support more printings of such subgraphs. One I would like to have is a printer for the AST subgraph that prints the AST-Subtree of a Node and its ancestor path. One attempt to implement this can be seen below, but does not return the correct types to yield a compilable solution:

fun Node.printAST(maxConnections: Int = 10): String {
 return this.printGraph(Node::astEdges, object: KProperty1<Node, MutableCollection<AstEdge<out Node>>> {
     override fun invoke(p1:Node) = p1.astParent?.astEdges?.filter { astE -> astE.end == p1 }?.toMutableList() ?: mutableListOf()
                                                                                                       },maxConnections)
}
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