add diff mode (#614)

* initial diff viewer

* test

* test

* name change

* new table show

* diff viewer

src/context/diff-context/use-diff.ts

@@ -0,0 +1,10 @@
+import { useContext } from 'react';
+import { diffContext } from './diff-context';
+
+export const useDiff = () => {
+    const context = useContext(diffContext);
+    if (context === undefined) {
+        throw new Error('useDiff must be used within an DiffProvider');
+    }
+    return context;
+};