Feat: basic keyboard controls and better WAI-ARIA defaults (#2333)

* feat(nodes): focusable and moveable with keys
* refactor(key-handling): cleanup, handle selections
* feat(edges): selectable with keys
* refactor(nodes-edges): cleanup keyboard controls and aria- attrs
* refactor(nodes): node needs to be selected for arrow keys
* refactor(minimap): create const for labelledby

closes #1033

examples/nextjs/pages/NestedNodes/index.tsx

@@ -158,8 +158,7 @@ const NestedFlow = () => {
       onEdgeClick={onEdgeClick}
       onConnect={onConnect}
       onNodeDragStop={onNodeDragStop}
-      className='react-flow-basic-example'
-      defaultZoom={1.5}
+      className="react-flow-basic-example"
       minZoom={0.2}
       maxZoom={4}
       onlyRenderVisibleElements={false}