[Chart.js] add view-value-change event

[IndraGunawan]

Q	A
Bug fix?	yes
New feature?	yes
Issues	Fix #...
License	MIT

I was following this tutorial https://ux.symfony.com/demos/live-component/chartjs and everything works fine until I want to modify the y axis label.

i read about this documentation that I can extend the default behaviour https://symfony.com/bundles/ux-chartjs/current/index.html#extend-the-default-behavior

it works on the initial chart render, but when I change some values the chart gets re-render, and the scale options that I added on pre-connect event get overwritten by $chart->setOptions([...]), when I tried to remove $chart->setOptions([...]) on PHP code completely to use the options fully from pre-connect, and I got this error

Uncaught TypeError: Stimulus Value "symfony--ux-chartjs--chart.viewValue" - Cannot convert undefined or null to object

hence I propose to introduce a new event that makes it able to add additional options while we are still using $chart->setOptions([...]) everytime the chart gets re-rendered

this is also fixed on viewValueChanged method if no $chart->setOptions([...]) provided

[smnandre]

Could you maybe add a test or two ?

[IndraGunawan]

@smnandre test added

[smnandre]

Looks good to me!

[kbond]

Thank you @IndraGunawan.