add util files

Author: sirkitree

core/src/utils/bignumber.ts

@@ -0,0 +1,9 @@
+import BigNumber from 'bignumber.js';
+
+// Re-export BigNumber constructor
+export const BN = BigNumber;
+
+// Helper function to create new BigNumber instances
+export function toBN(value: string | number | BigNumber): BigNumber {
+    return new BigNumber(value);
+}

core/src/utils/youtube.ts

@@ -0,0 +1,3 @@
+import youtubeDl from 'youtube-dl-exec';
+
+export const youtube = (url: string, options?: any) => youtubeDl(url, options);