refactor(configmanager): rename UI project and split test projects

Rename ConfigManager to ConfigManager.Ui to match the Core/CLI/UI project
structure, and split the monolithic test project into Core.Tests,
Cli.Tests, and Ui.Tests to align with the source project organization.

NEW/src/Utils/JdeScoping.ConfigManager.Ui/App.axaml

@@ -0,0 +1,16 @@
+<Application xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:converters="clr-namespace:JdeScoping.ConfigManager.Ui.Converters"
+             x:Class="JdeScoping.ConfigManager.Ui.App"
+             RequestedThemeVariant="Dark">
+    <Application.Styles>
+        <FluentTheme />
+        <StyleInclude Source="avares://Avalonia.Controls.DataGrid/Themes/Fluent.xaml" />
+    </Application.Styles>
+    <Application.Resources>
+        <ResourceDictionary>
+            <!-- Converters -->
+            <converters:StringToBoolConverter x:Key="StringToBool" />
+        </ResourceDictionary>
+    </Application.Resources>
+</Application>