fix: Installations graphs responsiveness

[Quentame]

fixes #926 & fixes #973

How:

• Explicitly activate chart responsive mode
• use plugins.legend.position = "bottom" to move legend bellow the chart to let move space for both the chart and the legend
• use plugins.legend.labels.usePointStyle = true to reduce the legend item width (and better align with the chart style)
• For the extreme case of versionHistoryChart graph: use aspectRatio to let more vertical space for the graph (desktop) and for te legend (mobile)

A better solution would be to create/use an HTML Legend Plugin that will allow to pull the legend out of the Chart canvas, sort items, and scroll on items (doc), I've already did that on a project but it takes more time, will do it later.

Also:

• Code style cleanup with better reusability
  • row/col design inspired from the Bootstrap framework : https://getbootstrap.com/docs/5.3/layout/columns/
• Avoid inline styling
• Factorise plugins.tooltip.callbacks.footer into tooltipFooterCallback()
• Change the div ID for the installations per countries from svgMap (?) to installationsPerCountry

ChartJS Doc:

• https://www.chartjs.org/docs/latest/configuration/legend.html
• https://www.chartjs.org/docs/latest/configuration/responsive.html

BEFORE	AFTER
desktop	desktop
mobile iPhone 12 Pro (width: 390px)	mobile iPhone 12 Pro (width: 390px)