Purpose
-----------
Currently, we have reports that depict the status of a
project at a certain point in time, but we don't have any reports
representing the actual progress of the project in time.
## Details
### Burndown Chart
A burndown chart is added in the reporting menu, this chart would help users see
the evolution of the project and determine whether it is on the
right track or not.
### Stacked in line chart
Currently, we can stacked in bar chart but not in line and pie charts. Here, the stacked will be also available in the line chart for the burndown chart.
Some unit tests in JS are added to keep the stacked in line chart of the burndown chart.
### Disable the pie chart in this reporting
This chart is not useful for this reporting, thus, the button has been hidden.
### Move constants and functions in own JS file
In web module, the GraphRenderer file contains some constants and functions used in the renderer of the graph view, these constants and functions are moved in new file called graph_utils.js to easily export these.
task-2458017
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I confirm I have signed the CLA and read the PR guidelines at www.odoo.com/submit-pr
closesodoo/odoo#68343
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>