wallet2: unlock keys file before calling verify_password (needed for Windows)

Also added notes to WalletManager::verifyWalletPassword (which afaik seems unused
by anyone at the moment) regarding the need to unlock the keys file beforehand.

src/wallet/api/wallet.cpp

@@ -2205,6 +2205,20 @@ void WalletImpl::keyReuseMitigation2(bool mitigation)
     m_wallet->key_reuse_mitigation2(mitigation);
 }
 
+bool WalletImpl::lockKeysFile()
+{
+    return m_wallet->lock_keys_file();
+}
+
+bool WalletImpl::unlockKeysFile()
+{
+    return m_wallet->unlock_keys_file();
+}
+
+bool WalletImpl::isKeysFileLocked()
+{
+    return m_wallet->is_keys_file_locked();
+}
 } // namespace
 
 namespace Bitmonero = Monero;