fix SvgCssUri fallback

[myou11]

Summary

When using the SvgCssUri component, specifying fallback does not render the fallback component in the case of an error.

I looked through the source code and believe this is because SvgCssUri is rendering a SvgCss

react-native-svg/src/css.tsx

Line 712 in 22f4733

return <SvgCss xml={xml} override={props} />;

which renders a SvgAst

react-native-svg/src/css.tsx

Line 696 in 22f4733

return <SvgAst ast={ast} override={override || props} />;

which does not use the fallback prop

react-native-svg/src/xml.tsx

Line 96 in 22f4733

export function SvgAst({ ast, override }: AstProps) {

This fix copies over the error handling code from SvgUri so SvgCssUri can render a fallback on error. I tested the change in my project and this works like it does for SvgUri

Test Plan

I tested this in my own project and I would have tested in this repo but not exactly sure how to run the tests in TestsExample. I went into that directory and ran yarn test but the setup seems to be broken.

Compatibility

OS	Implemented
iOS	✅
Android	✅

Checklist

• I have tested this on a device and a simulator
• I added documentation in README.md
• I updated the typed files (typescript)
• I added a test for the API in the __tests__ folder

[WoLewicki]

@myou11 can you resolve the conflicts? We recently changed the repo structure so you'll have to move the code.

[myou11]

@WoLewicki np, fixed now!