Merge bitcoin-core/gui#171: Use layout manager for Create Wallet dialog

d4feb68 qt: Use layout manager for Create Wallet dialog (Hennadii Stepanov)

Pull request description:

  On master (e75f91e) not using layout manager causes problems with resizing:

  ![Screenshot from 2021-01-01 13-03-13](https://user-images.githubusercontent.com/32963518/103437728-ce1d4580-4c33-11eb-8915-1e9482775653.png)
  ![Screenshot from 2021-01-01 13-03-26](https://user-images.githubusercontent.com/32963518/103437730-d6758080-4c33-11eb-9e0f-87d0dd487fcb.png)

  Also text labels are not resized properly on some window managers (bitcoin#20777), or if their lengths are changed (after translation).

  This PR introduces a standard layout manager for the "Create Wallet" dialog that fixes all layout issues (actually, the `createwalletdialog.ui` has been re-written from scratch):

  ![Screenshot from 2021-01-01 13-10-03](https://user-images.githubusercontent.com/32963518/103437822-d0cc6a80-4c34-11eb-84fd-fcb10a16d9ef.png)
  ![Screenshot from 2021-01-06 23-50-36](https://user-images.githubusercontent.com/32963518/103823090-0b416780-507a-11eb-89dd-3f48a358e168.png)

  Additional visual changes:
  - advanced options are grouped in `QGroupBox` (bitcoin-core/gui#96 (comment))
  - enabled the [size grip](https://doc.qt.io/qt-5/qsizegrip.html#details)

  Fix bitcoin#20777

ACKs for top commit:
  jarolrod:
    ACK d4feb68
  Sjors:
    re-tACK d4feb68
  promag:
    Tested ACK d4feb68 on macos.

Tree-SHA512: 4c055962e49f88624900b880b33a866976d224628784593428b712d2e94563d77ddefddea3397134d20e72f738a8cf9aa885c1272fd9ffc90213c104435fb9f4

src/qt/forms/createwalletdialog.ui

@@ -100,22 +100,14 @@
        </widget>
       </item>
       <item>
-        <widget class="QCheckBox" name="descriptor_checkbox">
-         <property name="geometry">
-          <rect>
-           <x>20</x>
-           <y>140</y>
-           <width>171</width>
-           <height>22</height>
-          </rect>
-         </property>
-         <property name="toolTip">
-          <string>Use descriptors for scriptPubKey management</string>
-         </property>
-         <property name="text">
-          <string>Descriptor Wallet</string>
-         </property>
-        </widget>
+       <widget class="QCheckBox" name="descriptor_checkbox">
+        <property name="toolTip">
+         <string>Use descriptors for scriptPubKey management</string>
+        </property>
+        <property name="text">
+         <string>Descriptor Wallet</string>
+        </property>
+       </widget>
       </item>
      </layout>
     </widget>