Merge bitcoin-core/gui#213: qt: Add Copy Address Action to Payment Requests

e348d7ea2c qt: Add Copy Address Action to Payment Requests (Jarol Rodriguez)

Pull request description:

  Currently, the only way to copy the address of a payment request is to double-click on the payment request and then click on the copy address button. This PR adds a convenient context menu action to copy the address of a payment request.

  | Master        | PR                 |
  | ----------- | ------------ |
  |<img width="169" alt="Screen Shot 2021-02-18 at 8 33 08 PM" src="https://user-images.githubusercontent.com/23396902/108444489-b6703f80-7228-11eb-8684-945fbcd04772.png"> |<img width="169" alt="Screen Shot 2021-02-18 at 8 33 50 PM" src="https://user-images.githubusercontent.com/23396902/108444505-c12ad480-7228-11eb-9eee-473fee877ad7.png">|

ACKs for top commit:
  hebasto:
    re-ACK e348d7ea2c, only suggested changes since my [previous](https://github.com/bitcoin-core/gui/pull/213#pullrequestreview-595520204) review.

Tree-SHA512: 2b75930ca326ef1d695afc1c6f25853ef55d06d20b66c3c3c372188a6cdfa4686c07f9c56824b766e46b660c731f8a9c2e5b935aa26b316fd46f9e396b29b802

src/qt/receivecoinsdialog.h

@@ -67,6 +67,7 @@ private Q_SLOTS:
     void updateDisplayUnit();
     void showMenu(const QPoint &point);
     void copyURI();
+    void copyAddress();
     void copyLabel();
     void copyMessage();
     void copyAmount();