Checklist

• I linked PR with a related issue
• I added multiple screenshots/screencasts of my UI changes

Motivation and Context

This PR completes #70

Description

• Package node can have multiple child nodes
• A Child node can be extracted from the parent node
• A Child node can be added as a child of another node
• Drag and drop actions on nodes can resize parent and their parent nodes recursively
• Increasing one node's width and height resized its parent's width and height
• Package node's name can be edited from a popover

Steps for Testing

• Add Package node to canvas
• Add another node from side node into package
• If cursor is on the package element, new node should be added as a child of the package node.
• If added node causes a overflow, package node should resize to cover
• Add extra and recursive package nodes
• Drag nodes from one package to another
• Observe parents are changing.
• When a node is a child of another node, during drag event of a parent, all of its child nodes should move with the parent
• Select one node element and edit it's name from popover

Screenshots