Add additional primitives

[techniq]

Along with Circle, Rect, etc, it would be nice to add a few more (while any of these can be implemented in the users project as well). Useful with new Dagre layout, and to have render context agnostic constructs (support Svg and Canvas).

• Image
  • https://developer.mozilla.org/en-US/docs/Web/SVG/Element/image
  • https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/drawImage
  • GeoTile
• Ellipse
  • https://developer.mozilla.org/en-US/docs/Web/SVG/Element/ellipse
  • https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/ellipse
• Diamond
  • https://developer.mozilla.org/en-US/docs/Web/SVG/Element/polygon
  • https://www.w3schools.com/graphics/svg_polygon.asp
• Polygon (5, 6, 8 sided, etc)
  • https://svelte.dev/playground/c5e2694a502942e29e92d9c5d2f83692?version=5.13.0
• Star
  • https://svelte.dev/playground/c5e2694a502942e29e92d9c5d2f83692?version=5.13.0