Make top margin consistent across Neochat settings

This standardizes on the same value used for KirigamiAddons pages like AboutKDE and About, namely largeSpacing * 4.

Now, when switching between settings pages you no longer have settings inconsistently changing heights willy nilly, header notwithstanding.

The only page that's missing is the Spellchecking page, as that needs to be fixed in Kirigami Addons' private Sonnet page.

src/settings/GlobalNotificationsPage.qml

@@ -23,7 +23,7 @@ FormCard.FormCardPage {
     }
 
     FormCard.FormCard {
-        Layout.topMargin: Kirigami.Units.largeSpacing
+        Layout.topMargin: Kirigami.Units.largeSpacing * 4
         FormCard.FormCheckDelegate {
             text: i18n("Enable notifications for this account")
             description: i18n("Whether push notifications are generated by your Matrix server")

src/settings/NeoChatSecurityPage.qml

@@ -26,7 +26,7 @@ FormCard.FormCardPage {
     }
 
     FormCard.FormCard {
-        Layout.topMargin: Kirigami.Units.largeSpacing
+        Layout.topMargin: Kirigami.Units.largeSpacing * 4
         FormCard.FormButtonDelegate {
             id: ignoredUsersDelegate
             text: i18nc("@action:button", "Ignored Users")

src/settings/NetworkProxyPage.qml

@@ -16,7 +16,7 @@ FormCard.FormCardPage {
     property bool proxyConfigChanged: false
 
     FormCard.FormCard {
-        Layout.topMargin: Kirigami.Units.largeSpacing
+        Layout.topMargin: Kirigami.Units.largeSpacing * 4
 
         FormCard.FormRadioDelegate {
             id: systemDefault