feat: add file preview modal (#945)

app/assets/javascripts/utils/concatenateUint8Arrays.ts

@@ -0,0 +1,14 @@
+export const concatenateUint8Arrays = (arrays: Uint8Array[]) => {
+  const totalLength = arrays
+    .map((array) => array.length)
+    .reduce((prev, next) => prev + next, 0);
+
+  const concatenatedArray = new Uint8Array(totalLength);
+  let offset = 0;
+  arrays.forEach((array) => {
+    concatenatedArray.set(array, offset);
+    offset += array.length;
+  });
+
+  return concatenatedArray;
+};