Conic gradients

还没有人认领这个 Issue。

This could be implemented using a few strategies, and we probably will want multiple so the user can pick what's best for their use case.

For support in all SVG viewers:
- A whole bunch of solid-colored pie slice triangles
- Rasterized as a base64 image at a set resolution

For support in some SVG viewers like browsers:
- `

`
- Possibly fewer pie slice triangles made out of linear gradient quads given CSS perspective transforms to turn them into triangles by pinching a pair of corners, however pure SVG only supports affine transforms


首先，将提议的 solid-triangle、rasterized base64、foreignObject/CSS 和 linear-gradient 策略与它们需要支持的 SVG 查看器进行比较。完成标准是选择并实现一种 conic-gradient 方法或一组方法，并定义受支持查看器的行为和用户选择。

由索引模型根据 Issue 内容生成。