Extend the existing SVG exporter so it can export frame-by-frame
animations as animated SVGs.
The animation data is fully contained inside the SVG. Each frame
is stored inside a `<g>` group that has the visibility turned off.
Then a `<use>` element displays the current frame using its `href`.
Inside the `<use>` element the `href` property is animated
with an `<animate>` tag that cycles through all the different frames.
To ensure unique element IDs within the file, the IDs of elements
user-defined names with user defined names are suffixed with
an continuously incrementing counter formatted as hex.
Pull Request: https://projects.blender.org/blender/blender/pulls/131173
8242eeb7ab