Convert images to use .qrc file, move images

All images have been moved to the /img/ folder in order to fully
separate qml from images. The .qrc file allows qml to use the images by
appending the qrc:/ prefix before the abstract path to the image.

Note that the .qrc file is also check at compile time, which further
enhances the confidence the lack of errors.

Some of the images are not used in the QML, but instead directly passed
through to the OpenVR API. These have not been added to the .qrc file.

src/res/qml/utilities_page/media_keys/MediaControllerKeys.qml

@@ -25,10 +25,10 @@ GroupBox {
         }
 
         RowLayout {
-            property string playPauseButtonPath: "outline_play_pause_white_24dp.svg"
-            property string stopButtonPath: "outline_stop_white_24dp.svg"
-            property string previousButtonPath: "outline_skip_previous_white_24dp.svg"
-            property string nextButtonPath: "outline_skip_next_white_24dp.svg"
+            property string playPauseButtonPath: "qrc:/media_keys/play_pause"
+            property string stopButtonPath: "qrc:/media_keys/stop"
+            property string previousButtonPath: "qrc:/media_keys/previous"
+            property string nextButtonPath: "qrc:/media_keys/next"
 
             MediaButton {
                 id: previousSongButton

src/res/qml/utilities_page/media_keys/outline_play_pause_white_24dp.svg

@@ -1,12 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!-- Generator: Adobe Illustrator 22.0.1, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
-<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
-	 viewBox="0 0 24 24" style="enable-background:new 0 0 24 24;" xml:space="preserve">
-<style type="text/css">
-	.st0{fill:none;}
-	.st1{fill:#FFFFFF;}
-</style>
-<path class="st0" d="M0,0h24v24H0V0z"/>
-<path class="st1" d="M5,8.6l5.3,3.4L5,15.4V8.6 M3,5v14l11-7L3,5z"/>
-<path class="st1" d="M14,19h2.3V5H14V19z M18.7,5v14H21V5H18.7z"/>
-</svg>

src/res/qml/utilities_page/media_keys/outline_skip_next_white_24dp.svg

@@ -1 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path fill="none" d="M0 0h24v24H0V0z"/><path fill="white" d="M6 18l8.5-6L6 6v12zm2-8.14L11.03 12 8 14.14V9.86zM16 6h2v12h-2z"/></svg>

src/res/qml/utilities_page/media_keys/outline_skip_previous_white_24dp.svg

@@ -1 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path fill="none" d="M0 0h24v24H0V0z"/><path fill="white" d="M6 6h2v12H6zm3.5 6l8.5 6V6l-8.5 6zm6.5 2.14L12.97 12 16 9.86v4.28z"/></svg>

src/res/qml/utilities_page/media_keys/outline_stop_white_24dp.svg

@@ -1 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path fill="none" d="M0 0h24v24H0V0z"/><path fill="white" d="M16 8v8H8V8h8m2-2H6v12h12V6z"/></svg>