Added theming support

src/modules/imageresizer/ui/Themes/Light.xaml

@@ -0,0 +1,30 @@
+<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+                    xmlns:markup="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
+                    xmlns:markupWithAssembly="clr-namespace:MahApps.Metro.Markup;assembly=MahApps.Metro"
+                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+                    xmlns:options="http://schemas.microsoft.com/winfx/2006/xaml/presentation/options"
+                    xmlns:system="clr-namespace:System;assembly=System.Runtime"
+                    mc:Ignorable="options">
+
+    <!--  Metadata  -->
+    <system:String x:Key="Theme.Name">Light.Accent1</system:String>
+    <system:String x:Key="Theme.Origin">PowerToysImageResizer</system:String>
+    <system:String x:Key="Theme.DisplayName">Accent1 (Light)</system:String>
+    <system:String x:Key="Theme.BaseColorScheme">Light</system:String>
+    <system:String x:Key="Theme.ColorScheme">Accent1</system:String>
+    <Color x:Key="Theme.PrimaryAccentColor">White</Color>
+
+    <SolidColorBrush x:Key="SecondaryBackgroundBrush" Color="#FFededed" />
+    <SolidColorBrush x:Key="PrimaryBackgroundBrush" Color="#FFe5e5e5" />
+    <SolidColorBrush x:Key="WindowBorderBrush" Color="#FFf7f7f7"/>
+    <SolidColorBrush x:Key="TitleBarSecondaryForegroundBrush" Color="#FF949494"/>
+
+    <SolidColorBrush x:Key="ListViewPointerOverBrush" Color="#e9e9e9"/>
+    <SolidColorBrush x:Key="ListViewPressedBrush" Color="#FFe5e5e5"/>
+
+    <SolidColorBrush x:Key="ColorControlBackgroundBrush" Color="#FFf9f9f9"/>
+
+    <SolidColorBrush x:Key="PrimaryForegroundBrush" Color="#FF000000" />
+    <SolidColorBrush x:Key="SecondaryForegroundBrush" Color="#FF949494" />
+</ResourceDictionary>