Migration: Chart Input/Output Formats

One issue during the migration of one of my dashboards was that the output and expected input from Dashboard 2.0's chart differ. Previously, it was possible to store the output of the chart and insert the stored values upon instance refresh. This is now different, which makes it hard to create a persistent dashboard. An easier migration would be possible if the old chart input format were also accepted.

See: https://flowfuse.com/blog/2023/05/persisting-chart-data-in-node-red/

## Requirements

- [ ] Dashboard 2.0 should accept the old chart input format alongside the new one.
- [x] Support for Year-Month-Date on X-axis
- [x] Output of the chart node should be compatible with input