Canvas: add alpha canvas panel and initial interfaces (#37279)

public/app/features/canvas/registry.ts

@@ -0,0 +1,15 @@
+import { Registry } from '@grafana/data';
+import { CanvasElementItem, CanvasElementOptions } from './element';
+import { iconItem } from './elements/icon';
+import { textBoxItem } from './elements/textBox';
+
+export const DEFAULT_CANVAS_ELEMENT_CONFIG: CanvasElementOptions = {
+  type: iconItem.id,
+  config: { ...iconItem.defaultConfig },
+  placement: { ...iconItem.defaultSize },
+};
+
+export const canvasElementRegistry = new Registry<CanvasElementItem>(() => [
+  iconItem, // default for now
+  textBoxItem,
+]);