wip, convert canvas app to react

src/apps/canvas/app.ts

src/apps/canvas/assembly-symmetry.ts

src/apps/canvas/component/app.tsx

src/apps/canvas/component/structure.tsx

src/apps/canvas/component/viewport.tsx

src/apps/canvas/index.html

src/apps/canvas/index.ts

src/apps/canvas/util.ts

src/apps/canvas/view.ts