webAuth [nfc]: Extract implementation into generateRandomToken function.

In an upcoming commit, we'll need to generate a random token (the
same implementation is fine), but without the OTP semantics.

Author: chrisbobbe

src/start/webAuth.js

@@ -27,9 +27,7 @@ import { base64ToHex, hexToAscii, xorHexStrings } from '../utils/encoding';
        https://chat.zulip.org/#narrow/stream/16-desktop/topic/desktop.20app.20OAuth/near/803919
  */
 
-// Generate a one time pad (OTP) which the server XORs the API key with
-// in its response to protect against credentials intercept
-export const generateOtp = async (): Promise<string> => {
+export const generateRandomToken = async (): Promise<string> => {
   if (Platform.OS === 'android') {
     return new Promise((resolve, reject) => {
       NativeModules.RNSecureRandom.randomBase64(32, (err, result) => {
@@ -45,6 +43,10 @@ export const generateOtp = async (): Promise<string> => {
   }
 };
 
+// Generate a one time pad (OTP) which the server XORs the API key with
+// in its response to protect against credentials intercept
+export const generateOtp = async (): Promise<string> => generateRandomToken();
+
 export const openBrowser = (url: string, otp: string) => {
   openLink(`${url}?mobile_flow_otp=${otp}`);
 };