Theme consistency overhaul:

- Add surface shift option, start from surface by default (previously
  was surfaceContainer). Old colors can be attained by changing it back
to "container" in theme colors
- Remove borders on surface elements, mostly
- Fix popup distances
- Use surfaceContainer/sch by default on widgets

Modules/DankDash/Overview/Card.qml

@@ -8,7 +8,7 @@ Rectangle {
     property int pad: Theme.spacingM
     
     radius: Theme.cornerRadius
-    color: Qt.rgba(Theme.surfaceVariant.r, Theme.surfaceVariant.g, Theme.surfaceVariant.b, 0.2)
+    color: Theme.surfaceContainerHigh
     border.color: Qt.rgba(Theme.outline.r, Theme.outline.g, Theme.outline.b, 0.08)
     border.width: 1