Fix Kirigami.Units.devicePixelRatio=1.3 when it should be 1.0 at 96dpi

Summary:
I recently noticed that `Kirigami.Units.devicePixelRatio` was `1.3` even though I was at the default 96dpi when writing a widget's config.

{F8287886}

There's 4 different `Units.qml`, and I'm not certain which does what. 2 are in `krigiami` and the other 2 are in `plasma-framework`.

```
$ locate /Units.qml | grep /usr/
/usr/lib/qt/qml/org/kde/kirigami.2/Units.qml
/usr/lib/qt/qml/org/kde/kirigami.2/styles/Plasma/Units.qml
/usr/lib/qt/qml/org/kde/kirigami.2/styles/org.kde.desktop/Units.qml
/usr/lib/qt/qml/org/kde/kirigami.2/styles/org.kde.desktop.plasma/Units.qml
```

* 2 years ago [`kirigami/src/controls/Units.qml`](https://github.com/KDE/kirigami/blame/master/src/controls/Units.qml#L75) (`/usr/lib/qt/qml/org/kde/kirigami.2/Units.qml`) was changed from `13/10 = 1.3` to multiply by `13*0.75` so that `9.75/10 = 0.975` (then `max(1, 0.975) = 1`).

-----

There's 2 files owned by `plasma-framework`. The `/styles/Plasma/Units.qml` binds PlasmaCore's `units.devicePixelRatio`, so that leaves `/styles/org.kde.desktop.plasma/Units.qml`.

```
$ pacman -Qo /usr/lib/qt/qml/org/kde/kirigami.2/styles/org.kde.desktop.plasma/Units.qml
/usr/lib/qt/qml/org/kde/kirigami.2/styles/org.kde.desktop.plasma/Units.qml is owned by plasma-framework 5.69.0-2
```

This patch edits the `org.kde.desktop.plasma` style, and fixes `qmlscene KirigamiDevicePixelRatioTest.qml`, and `plasmashell` widget configs, and `plasmoidviewer` widget configs.

The Kirigami patch is D29462

Test Plan:
You can edit `/usr/lib/qt/qml/org/kde/kirigami.2/styles/org.kde.desktop.plasma/Units.qml` then run:

* https://gist.github.com/Zren/621338b8cda7c550d7b43f8ea1ba71a7
* `qmlscene KirigamiDevicePixelRatioTest.qml`

and `Kirigami.Units.devicePixelRatio` should equal `1`.

Reviewers: #kirigami, mart

Reviewed By: #kirigami, mart

Subscribers: davidre, kde-frameworks-devel

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D29463

src/declarativeimports/kirigamiplasmadesktopstyle/Units.qml

@@ -27,6 +27,10 @@ import org.kde.kirigami 2.4
 pragma Singleton
 
 
+/**
+ * A set of values to define semantically sizes and durations
+ * @inherit QtQuick.QtObject
+ */
 QtObject {
     id: unitsRoot
 
@@ -85,7 +89,7 @@ QtObject {
      * use theme.mSize(theme.defaultFont), units.smallSpacing and units.largeSpacing.
      * The devicePixelRatio follows the definition of "device independent pixel" by Microsoft.
      */
-    property real devicePixelRatio: Math.max(1, (fontMetrics.font.pixelSize / fontMetrics.font.pointSize))
+    property real devicePixelRatio: Math.max(1, ((fontMetrics.font.pixelSize*0.75) / fontMetrics.font.pointSize))
 
     /**
      * units.longDuration should be used for longer, screen-covering animations, for opening and
@@ -113,8 +117,16 @@ QtObject {
      */
     readonly property int wheelScrollLines: __styleItem.styleHint("wheelScrollLines")
 
+    /**
+     * time in ms by which the display of tooltips will be delayed.
+     *
+     * @sa ToolTip.delay property
+     */
     property int toolTipDelay: 700
 
+    /**
+     * metrics used by the default font
+     */
     property variant fontMetrics: TextMetrics {
         text: "M"
         function roundedIconSize(size) {

src/declarativeimports/kirigamiplasmastyle/Units.qml

@@ -23,6 +23,10 @@ import QtQuick 2.4
 import org.kde.plasma.core 2.0 as PlasmaCore
 import org.kde.kirigami 2.4
 
+/**
+ * A set of values to define semantically sizes and durations
+ * @inherit QtQuick.QtObject
+ */
 QtObject {
     /**
      * The fundamental unit of space that should be used for sizes, expressed in pixels.
@@ -105,6 +109,11 @@ QtObject {
      */
     property int wheelScrollLines: 3
 
+    /**
+     * time in ms by which the display of tooltips will be delayed.
+     *
+     * @sa ToolTip.delay property
+     */
     property int toolTipDelay: Settings.tabletMode ? Qt.styleHints.mousePressAndHoldInterval : 700
 
     /**