[Feature] Sankey - How to group sankey data by fixed columns

### What problem does this feature solve?

As a user, I have tabular data that represents the flow of data from one type of entity to another.

### Example 1:
Imagine I have this table data.
The table column would create a column like layout for the sankey diagram like so:

ID | Source | Destination | Energy
-- | -- | -- | --
1 | feeding point | building 1 | 100
2 | feeding point | building 2 | 200
3 | building 1 | b1 floor 1 | 75
4 | building 1 | b1 floor 2 | 25
5 | building 2 | b2 floor 1 | 150
6 | building 2 | b2 floor 2 | 50

Which would output this:

## Example 2
Each table column maps to a level


### What does the proposed API look like?
Work in progress
.