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/CustomNode/index.tsx

@@ -29,6 +29,7 @@ const initBgColor = '#1A192B';
 
 const connectionLineStyle = { stroke: '#fff' };
 const snapGrid: SnapGrid = [16, 16];
+const defaultViewport = { x: 0, y: 0, zoom: 1.5 };
 
 const nodeTypes = {
   selectorNode: ColorSelectorNode,
@@ -141,7 +142,7 @@ const CustomNodeFlow = () => {
       connectionLineStyle={connectionLineStyle}
       snapToGrid={true}
       snapGrid={snapGrid}
-      defaultZoom={1.5}
+      defaultViewport={defaultViewport}
       fitView
     >
       <MiniMap