Merge bitcoin-core/gui#276: Elide long strings in their middle in the Peers tab

4e0613369f qt: Elide long strings in their middle in the Peers tab (Hennadii Stepanov)

Pull request description:

  The eliding of long addresses (Onion v3 etc) in the Peers tab in their middle was [discussed](https://github.com/bitcoin-core/gui/issues/262#issuecomment-810490396) in #262.

  On master (f0fa32450e):
  ![DeepinScreenshot_select-area_20210410141435](https://user-images.githubusercontent.com/32963518/114267903-24eea400-9a07-11eb-8c80-99f68d5cc522.png)

  With this PR:
  ![DeepinScreenshot_select-area_20210410140430](https://user-images.githubusercontent.com/32963518/114267796-83675280-9a06-11eb-921f-ca47c2075496.png)

  This PR suggests the minimal diff to achieve the goal. OTOH, this change in behavior is common for all columns in the Peers table, but it seems harmless.

ACKs for top commit:
  jarolrod:
    tACK 4e0613369f
  promag:
    Code review ACK 4e0613369f.

Tree-SHA512: 1d5a62afb1152029e69fccea2ae53dcb262a91724a5c03dfc4de8c409b280814d0c211c2f9a71f1a6e927f4ed571ba4ac311de9de8ebb797eaf1051674241bdb

src/qt/forms/debugwindow.ui

@@ -923,9 +923,15 @@
              <property name="tabKeyNavigation">
               <bool>false</bool>
              </property>
+             <property name="textElideMode">
+              <enum>Qt::ElideMiddle</enum>
+             </property>
              <property name="sortingEnabled">
               <bool>true</bool>
              </property>
+             <property name="wordWrap">
+              <bool>false</bool>
+             </property>
              <attribute name="horizontalHeaderHighlightSections">
               <bool>false</bool>
              </attribute>