Merge #18922: gui: Do not translate InitWarning messages in debug.log

78be8d97d3 util: Drop OpOriginal() and OpTranslated() (Hennadii Stepanov)
da16f95c3f gui: Do not translate InitWarning messages in debug.log (Hennadii Stepanov)
4c9b9a4882 util: Enhance Join() (Hennadii Stepanov)
fe05dd0611 util: Enhance bilingual_str (Hennadii Stepanov)

Pull request description:

  This PR forces the `bitcoin-qt` to write `InitWarning()` messages to the `debug.log` file in untranslated form, i.e., in English.

  On master (376294cde6):
  ```
  $ ./src/qt/bitcoin-qt -lang=nl -debug=vladidation -printtoconsole | grep 'vladi'
  Warning: Niet-ondersteunde logcategorie -debug=vladidation.
  2020-05-09T12:39:59Z Warning: Niet-ondersteunde logcategorie -debug=vladidation.
  2020-05-09T12:40:02Z Command-line arg: debug="vladidation"
  ```

  With this PR:
  ```
  $ ./src/qt/bitcoin-qt -lang=nl -debug=vladidation -printtoconsole | grep 'vladi'
  Warning: Unsupported logging category -debug=vladidation.
  2020-05-09T12:42:04Z Warning: Unsupported logging category -debug=vladidation.
  2020-05-09T12:42:35Z Command-line arg: debug="vladidation"
  ```

  ![Screenshot from 2020-05-09 15-42-31](https://user-images.githubusercontent.com/32963518/81474073-c7a50e00-920b-11ea-8775-c41122dacafe.png)

  Related to #16218.

ACKs for top commit:
  laanwj:
    ACK 78be8d97d3
  jonasschnelli:
    utACK 78be8d97d3
  MarcoFalke:
    ACK 78be8d97d3 📢

Tree-SHA512: 48e9ecd23c4dd8ec262e3eb94f8e30944bcc9c6c163245fb837b2e0c484d4d0b4f47f7abc638c14edc27d635d340ba3ee4ba4506b062399e9cf59a1564c98755

src/qt/walletcontroller.cpp

@@ -248,7 +248,7 @@ void CreateWalletActivity::finish()
     if (!m_error_message.original.empty()) {
         QMessageBox::critical(m_parent_widget, tr("Create wallet failed"), QString::fromStdString(m_error_message.translated));
     } else if (!m_warning_message.empty()) {
-        QMessageBox::warning(m_parent_widget, tr("Create wallet warning"), QString::fromStdString(Join(m_warning_message, "\n", OpTranslated)));
+        QMessageBox::warning(m_parent_widget, tr("Create wallet warning"), QString::fromStdString(Join(m_warning_message, Untranslated("\n")).translated));
     }
 
     if (m_wallet_model) Q_EMIT created(m_wallet_model);
@@ -289,7 +289,7 @@ void OpenWalletActivity::finish()
     if (!m_error_message.original.empty()) {
         QMessageBox::critical(m_parent_widget, tr("Open wallet failed"), QString::fromStdString(m_error_message.translated));
     } else if (!m_warning_message.empty()) {
-        QMessageBox::warning(m_parent_widget, tr("Open wallet warning"), QString::fromStdString(Join(m_warning_message, "\n", OpTranslated)));
+        QMessageBox::warning(m_parent_widget, tr("Open wallet warning"), QString::fromStdString(Join(m_warning_message, Untranslated("\n")).translated));
     }
 
     if (m_wallet_model) Q_EMIT opened(m_wallet_model);