[svg] Implement <image> element

https://www.w3.org/TR/SVG11/struct.html#ImageElement

Supported reference types are data and non-local URIs. Resource loading
requires a ResourceProvider to have been set on the render context.

Not handled in this CL:
- preserveAspectRatio support
- SVG reference types (i.e. '<image xlink:href="file.svg" ...')

Bug: skia:10842
Change-Id: Ieec7569f60516b01fc847f4160d0733b1e3a1cf5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/364576
Commit-Queue: Tyler Denniston <tdenniston@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
6 files changed