feat: remove token prefix util (#2191)

* feat: remove token prefix util

* fix: token substring

* fix: speed up unit tests

util/token.ts

@@ -0,0 +1,9 @@
+/** Removes the Bot before the token. */
+export function removeTokenPrefix(token?: string, type: "GATEWAY" | "REST" = "REST"): string {
+  // If no token is provided, throw an error
+  if (!token) throw new Error(`The ${type} was not given a token. Please provide a token and try again.`);
+  // If the token does not have a prefix just return token
+  if (!token.startsWith("Bot ")) return token;
+  // Remove the prefix and return only the token.
+  return token.substring(token.indexOf(" ") + 1);
+}