feat(drag): maintainAspectRatio

[kurkle]

Add optional maintainAspectRatio boolean to drag options, which forces the drag rectangle to same aspect ration with chartArea.

closed: #115

[github-actions[bot]]

Size Change: +858 B (+3.97%)

Total Size: 22.5 kB

Filename	Size	Change
dist/chartjs-plugin-zoom.esm.js	8.58 kB	+323 B (+3.91%)
dist/chartjs-plugin-zoom.js	8.73 kB	+321 B (+3.82%)
dist/chartjs-plugin-zoom.min.js	5.16 kB	+214 B (+4.33%)

_{compressed-size-action}