Merge #1588: [GUI][Bug] Fix editing of CS address labels

805e436 [GUI][Bug] Fix editing of CS address labels (Fuzzbawls)

Pull request description:

  Fixes a bug that prevented the editing of Cold Staking address labels in
  the address book due to the passing of an empty purpose, which
  `CWallet::ParseIntoAddress()` needs in order to determine if an address
  is a cold staking type address.

ACKs for top commit:
  random-zebra:
    ACK 805e436
  furszy:
    utACK 805e436

Tree-SHA512: 73adff6e13ecb5232c49ba9be7a082e1f8b4f603d9d42c664ee98bd144d53e5cbf9b129524eca0d6fa017f9f9b34b83872e4a7b31bb1aa33f0fb1b02cf7e0aa8

src/wallet/wallet.cpp

@@ -2890,10 +2890,10 @@ bool CWallet::SetAddressBook(const CTxDestination& address, const std::string& s
             mapAddressBook[address].purpose = strPurpose;
     }
     NotifyAddressBookChanged(this, address, strName, ::IsMine(*this, address) != ISMINE_NO,
-        strPurpose, (fUpdated ? CT_UPDATED : CT_NEW));
+            mapAddressBook.at(address).purpose, (fUpdated ? CT_UPDATED : CT_NEW));
     if (!fFileBacked)
         return false;
-    std::string addressStr = ParseIntoAddress(address, strPurpose).ToString();
+    std::string addressStr = ParseIntoAddress(address, mapAddressBook.at(address).purpose).ToString();
     if (!strPurpose.empty() && !CWalletDB(strWalletFile).WritePurpose(addressStr, strPurpose))
         return false;
     return CWalletDB(strWalletFile).WriteName(addressStr, strName);