`@neodx/svg` - Add support for extracting all referenced defs to inline strings

[secundant]

The issue arises from the missing <defs> section in the SVG, within the <use> Shadow DOM. Browsers, at least Chrome, ignore this silently. Possible solutions include:

• ?? Accumulating all elements as a runtime string (is it possible to paste defs into the document?)

• Generating an inline sprite for future injection into HTML.

• https://stackoverflow.com/questions/24806913/how-can-i-refer-to-an-internal-gradient-definition-inside-an-svg-sprite-symbol

• https://github.com/w0rm/gulp-svgstore/issues/31#issuecomment-77020501

Closes #69

[7iomka]

That's the main reason I inline my sprites, but bloating every page without caching for the sake of such cases is impractical. In the end I decided to insert such images as React components for svgs with gradient and etc, and for rest to keep use sprites in external file

[Mottoweb]

Any update on this? I can't get linearGradient to work as expected