qml: use signal based navigation in settings with subpages

Here, pages are clearly contained, but the logic of moving to
SettingsDeveloper from within SettingsAbout and SettingsProxy from
within SettingsConnection is still contained here within the definitions
of SettingsAbout and SettingsConnection. While all pages are
independently still usable, we do want to iron out this one kink in a
follow-up.

Author: jarolrod

src/qml/components/AboutOptions.qml

@@ -8,6 +8,8 @@ import QtQuick.Layouts 1.15
 import "../controls"
 
 ColumnLayout {
+    id: root
+    signal next
     spacing: 4
     Setting {
         id: websiteLink
@@ -69,7 +71,7 @@ ColumnLayout {
             color: gotoDeveloper.stateColor
         }
         onClicked: {
-            aboutSwipe.incrementCurrentIndex()
+            root.next()
         }
     }
     ExternalPopup {

src/qml/components/ConnectionSettings.qml

@@ -8,6 +8,8 @@ import QtQuick.Layouts 1.15
 import "../controls"
 
 ColumnLayout {
+    id: root
+    signal next
     spacing: 4
     Setting {
         Layout.fillWidth: true
@@ -69,6 +71,6 @@ ColumnLayout {
         actionItem: CaretRightIcon {
             color: gotoProxy.stateColor
         }
-        onClicked: connectionSwipe.incrementCurrentIndex()
+        onClicked: root.next()
     }
 }

src/qml/pages/settings/SettingsAbout.qml

@@ -32,7 +32,9 @@ Item {
             description: qsTr("Bitcoin Core is an open source project.\nIf you find it useful, please contribute.\n\n This is experimental software.")
             descriptionMargin: 20
             detailActive: true
-            detailItem: AboutOptions {}
+            detailItem: AboutOptions {
+                onNext: aboutSwipe.incrementCurrentIndex()
+            }
         }
         SettingsDeveloper {
             id: about_developer

src/qml/pages/settings/SettingsConnection.qml

@@ -31,7 +31,9 @@ Item {
             headerText: qsTr("Connection settings")
             headerMargin: 0
             detailActive: true
-            detailItem: ConnectionSettings {}
+            detailItem: ConnectionSettings {
+                onNext: connectionSwipe.incrementCurrentIndex()
+            }
         }
         SettingsProxy {
             onBackClicked: {