[FIX] charts: fix smart chart engine

We have a "Smart chart engine" that automatically suggests a chart
type and configuration based on the selected data. There were a bunch
of issues with it:

- some selected columns were sometime missing from the chart definition
- the chart created was sometime empty
- the order of the selected columns has totally ignored, leading to some
strange definitions with a dataset [col1, col3] and labels on col2
- we used a `createBaseChart` helper that casted an object into a
`ChartDefinition`, skipping the typing and leading to wrong chart
definitions with missing properties.
- some rules were strange or inconsistent

This commit fixes those issues, making the rules simpler and more
consistent, while adding some docstring to explain the desired
behavior.

closes #7361

Task: 5079093
X-original-commit: d6535bd
Signed-off-by: Pierre Rousseau (pro) <pro@odoo.com>
Signed-off-by: Adrien Minne (adrm) <adrm@odoo.com>

Author: hokolomopo