Tm/upgrade-ledger-2fa (#976)

* Change ledger guardian signing to cross window

* Resolve comments

Author: arhtudormorar

docs/sdk-and-tools/sdk-dapp/internal-processes/guardians.md

@@ -44,16 +44,22 @@ All signing providers (except Ledger) take care internally of formatting the tra
 After formatting the transaction and applying the signature provided by the Ledger device, the transaction must be signed by the Guardian. This is done by sending the transaction (or transactions array) to the web wallet 2FA hook. The web wallet will then prompt the user to sign the transaction with the Guardian account, and respond with the signed transaction.
 
 ```js
-import { WalletProvider } from '@multiversx/sdk-web-wallet-provider';
+import { CrossWindowProvider } from "@multiversx/sdk-web-wallet-cross-window-provider";
 
-const walletProvider = new WalletProvider('https://wallet.multiversx.com/dapp/init');
-walletProvider.guardTransactions(transactions, {
-    callbackUrl: encodeURIComponent('https://my-dapp.com'),
-});
-```
-Once transactions are back from the web wallet, they can be retrieved as follows:
+// instantiate wallet cross-window provider
+await CrossWindowProvider.getInstance().init();
+const crossWindowProvider = CrossWindowProvider.getInstance();
+crossWindowProvider.setWalletUrl(WALLET_PROVIDER_URL);
 
-```js
-const signedTransactions = new WalletProvider('https://wallet.multiversx.com/dapp/init').getTransactionsFromWalletUrl();
-```
+// set sender
+const ledgerSenderBech32 = await this.hwProvider.getAddress();
+const sender = Address.newFromBech32(ledgerSenderBech32); // or "erd1...abc" witohut awaiting `getAddress()`
+crossWindowProvider.setAddress(sender);
+
+// To complete the transaction, the user will sign using their Ledger device. This requires an additional step: a confirmation popup will appear, prompting the user to approve the action, after which a new tab will open in the browser.
+crossWindowProvider.setShouldShowConsentPopup(true);
 
+const guardedTransactions = await crossWindowProvider.guardTransactions(
+    signedTransactions
+);
+```