✨(y-provider) create utils function toBase64

Add utility function to convert BitArray to Base64 string.
This is required for creating Base64-encoded documents,
as the frontend do.

src/frontend/servers/y-provider/src/utils.ts

@@ -7,3 +7,7 @@ export function logger(...args: any[]) {
     console.log(...args);
   }
 }
+
+export const toBase64 = function (str: Uint8Array) {
+  return Buffer.from(str).toString('base64');
+};