shapes folder, move tools into shape defs (#1574)

This diff adds a new property to `defineShape`: `tool`.

The tool prop allows shapes to bring a tool along with them as part of
their definition. E.g. the draw shape isn't much use without the draw
tool, so adding the draw shape to your app gives you the draw tool tool.

As part of this, i renamed the `shapeutils` folder to just `shapes`, and
moved a bunch of shape-specific tools from the tools folder into the
shapes folder. This more closely reflects how things will be once we
move our default shapes out of core for tldraw-zero.

### Change Type

- [x] `patch` — Bug fix

### Test Plan

Tested locally

### Release Notes

n/a

packages/editor/src/lib/components/ShapeIndicator.tsx

@@ -8,7 +8,7 @@ import {
 } from 'signia-react'
 import { useEditor } from '../..'
 import type { Editor } from '../editor/Editor'
-import { ShapeUtil } from '../editor/shapeutils/ShapeUtil'
+import { ShapeUtil } from '../editor/shapes/ShapeUtil'
 import { useEditorComponents } from '../hooks/useEditorComponents'
 import { OptionalErrorBoundary } from './ErrorBoundary'