qml: Introduce Storage OptionButton that represents custom prune target

This allows for a new OptionButton to be shown in StorageOptions when
the user has going into detailed settings during onboarding and chosen
a custom prune target

Author: jarolrod

src/qml/components/StorageOptions.qml

@@ -8,6 +8,9 @@ import QtQuick.Layouts 1.15
 import "../controls"
 
 ColumnLayout {
+    id: root
+    property bool customStorage: false
+    property int customStorageAmount
     ButtonGroup {
         id: group
     }
@@ -18,7 +21,7 @@ ColumnLayout {
         text: qsTr("Reduce storage")
         description: qsTr("Uses about 2GB. For simple wallet use.")
         recommended: true
-        checked: true
+        checked: !root.customStorage && optionsModel.prune
         onClicked: {
             optionsModel.prune = true
             optionsModel.pruneSizeGB = 2
@@ -32,9 +35,25 @@ ColumnLayout {
         Layout.fillWidth: true
         ButtonGroup.group: group
         text: qsTr("Store all data")
+        checked: !optionsModel.prune
         description: qsTr("Uses about 550GB. Support the network.")
         onClicked: {
             optionsModel.prune = false
         }
     }
+    Loader {
+        Layout.fillWidth: true
+        active: root.customStorage
+        visible: active
+        sourceComponent: OptionButton {
+            ButtonGroup.group: group
+            checked: root.customStorage && optionsModel.prune
+            text: qsTr("Custom")
+            description: qsTr("Storing recent blocks up to %1GB").arg(root.customStorageAmount)
+            onClicked: {
+                optionsModel.prune = true
+                optionsModel.pruneSizeGB = root.customStorageAmount
+            }
+        }
+    }
 }

src/qml/components/StorageSettings.qml

@@ -8,6 +8,9 @@ import QtQuick.Layouts 1.15
 import "../controls"
 
 ColumnLayout {
+    id: root
+    property bool customStorage: false
+    property int customStorageAmount
     spacing: 4
     Setting {
         Layout.fillWidth: true
@@ -42,6 +45,8 @@ ColumnLayout {
                 if (parseInt(text) < 1) {
                     pruneTargetSetting.showErrorText = true
                 } else {
+                    root.customStorage = true
+                    root.customStorageAmount = parseInt(text)
                     optionsModel.pruneSizeGB = parseInt(text)
                     pruneTargetSetting.forceActiveFocus()
                     pruneTargetSetting.showErrorText = false

src/qml/pages/onboarding/OnboardingStorageAmount.qml

@@ -33,6 +33,8 @@ Page {
             detailItem: ColumnLayout {
                 spacing: 0
                 StorageOptions {
+                    customStorage: advancedStorage.loadedDetailItem.customStorage
+                    customStorageAmount: advancedStorage.loadedDetailItem.customStorageAmount
                     Layout.maximumWidth: 450
                     Layout.alignment: Qt.AlignCenter
                 }
@@ -47,6 +49,7 @@ Page {
             buttonMargin: 20
         }
         SettingsStorage {
+            id: advancedStorage
             navRightDetail: NavButton {
                 text: qsTr("Done")
                 onClicked: {