Feature/wasm svg support

[JaminMartin]

After some great help from @LukaOber in #211 I have added the ability to choose the rendering backend for the WasmRenderer

Key changes at the user level:

let renderer = WasmRenderer::new(600, 400).renderer(Renderer::Svg);

The user can now specify the rendering backend, if the .renderer method is not added, the current default behaviour is used (i.e. defaults to canvas

Under the hood, the WasmRenderer now accepts additional init options, not just its size. I have also renamed ChartSize to InitOptions to reflect this.

I believe some of these could be renamed further, e.g. let renderer = WasmRenderer::new(600, 400).backend(Renderer::Svg);
The Renderer enum could also be renamed if there is a more appropriate name.

I have updated the Leptos example to include this and it works well, replicating the same results as was provided by #211
This should work for all Wasm supporting frameworks e.g Dioxus, Yew etc.

[LukaOber]

CI is failing due to another problem. I will review the code on the weekend.

[JaminMartin]

@LukaOber Is this still failing due to another issue? or something I have done? happy to fix if there is an issue.

[JaminMartin]

@LukaOber any progress on this? Understandable if you are busy!