Feature: show extra data for nodes and flows in the diagram

[jsolaas]

We want to be able to show extra data for nodes and flows in the diagram

• We need a separate data object containing the information. This should be a map from node id to the data
• The data should be used to set the width of the flows creating a sankey diagram
• We might also want to display some numbers from the data on the nodes directly
• The data is time-based. The timeline should use these timesteps instead of the current steps/continual. The selected datetime should be used to get the current value for the nodes

The structure of this data will probably be something like this (TBD):

const test: DiagramData = {
  timesteps: ['01.01.2020', '01.01.2021'],
  nodes: {
    'node id 1': [{value1: 8, value2: 6}], // matched with timesteps on index
  }
}

interface DataPoint {
  value: number;
  unit: string;
}

interface NodeData {
  value1: number, // Might want to use DataPoint instead to include info such as unit.
  value2: number,
}

interface DiagramData {
  timesteps: string[];
  nodes: {[nodeId: string]: NodeData[]}
}