See call for testing

Summary

Original issue: #8850
Implementation: #15091

This changes Cargo timing report renderer from HTML canvas to SVG, improving the performance of rendering large dependency graph, as well as hovering dependency lines.

Currently canvas is still the default, and there is a toggle switching between them during the call-for-testing period

Unresolved Issues

• Call-for-testing
• Remove legacy canvas renderer
• Understand our minimum supported browser version
  • Safari 12 on an old Intel Macbook running macOS 10.12 Tracking Issue for timing report SVG render backend #16440 (comment)

Future Extensions

• A detailed view when hover on dependency lines: Experiment: Render timing pipeline in SVG #15091 (comment)
• Text selection: Tracking Issue for timing report SVG render backend #16440 (comment)
• Switch to HTML template library for better maintainability?
• Switch to a frontend framework for better maintainability?

About tracking issues

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They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.