Add SVG component support

[jamilahmadzai]

Summary:

• Add an Svg root component backed by QSvgWidget.
• Serialize SVG-like React children to XML and re-render on prop or child updates.
• Export common shape components (Rect, Circle, Path, G, Group, and others) plus SvgText for SVG text without conflicting with the existing Text component.
• Support full SVG documents through src, buffer, or content.
• Document the inline SVG API in the README.

Acceptance coverage:

• Implements the MVP discussed in issue Support for svg in React code. #31 by generating SVG XML and loading it through Qt SVG rendering.
• Avoids a separate plugin dependency because @nodegui/nodegui already exports QSvgWidget.
• Supports the common chart/icon primitives needed for inline SVG-style React trees.

IssueHunt: https://oss.issuehunt.io/r/nodegui/react-nodegui/issues/31
Payment: IssueHunt bounty-platform payout to GitHub user @jamilahmadzai.

Fixes #31

Validation:

• yarn build