feat: when a node of the graph is selected, the border of the node is highlighted. #918 (#1125)

### What problem does this PR solve?

feat: when a node of the graph is selected, the border of the node is
highlighted. #918

### Type of change


- [x] New Feature (non-breaking change which adds functionality)

web/src/pages/flow/canvas/node/index.less

   }
 }
 .selectedNode {
-  border-color: #1677ff;
+  border: 1px solid rgb(59, 118, 244);
 }
 
 .handle {

web/src/pages/flow/canvas/node/index.tsx

       </Handle>
       <Handle type="source" position={Position.Bottom} id="a" isConnectable />
       <div>
-        <Space>
+        <Space size={4}>
           <OperatorIcon
             name={data.label as Operator}
             fontSize={12}