Fix Global Usings One Per Project (#3648)

Issues with a single file where invalid usings exist.

<!-- Please be sure to read the
[Contribute](https://github.com/reactiveui/reactiveui#contribute)
section of the README -->

**What kind of change does this PR introduce?**
<!-- Bug fix, feature, docs update, ... -->

Fix

**What is the current behavior?**
<!-- You can also link to an open issue here. -->

A single GlobalUsing file is used

**What is the new behavior?**
<!-- If this is a feature change -->

Multiple GlobalUsing files are used to remove the issue where usings are
included that are invalid for some projects

**What might this PR break?**

none expected

**Please check if the PR fulfills these requirements**
- [ ] Tests for the changes have been added (for bug fixes / features)
- [ ] Docs have been added / updated (for bug fixes / features)

**Other information**:

Author: ChrisPulman

src/Directory.build.props

@@ -70,10 +70,6 @@
     <None Include="$(MSBuildThisFileDirectory)..\README.md" Pack="true" PackagePath="\" />
   </ItemGroup>
 
-  <ItemGroup Condition="$(MSBuildProjectName.Contains('Fody')) != 'true'">
-    <Compile Include="$(MSBuildThisFileDirectory)GlobalUsings.cs" />
-  </ItemGroup>
-
   <ItemGroup>	
     <PackageReference Include="Nerdbank.GitVersioning" Version="3.6.133" PrivateAssets="all" />	
     <PackageReference Include="stylecop.analyzers" Version="1.2.0-beta.507" PrivateAssets="all" />

src/ReactiveUI.AndroidSupport/GlobalUsings.cs

@@ -0,0 +1,16 @@
+// Copyright (c) 2023 .NET Foundation and Contributors. All rights reserved.
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+global using global::Splat;
+global using global::System;
+global using global::System.Collections.Generic;
+global using global::System.ComponentModel;
+global using global::System.Diagnostics.CodeAnalysis;
+global using global::System.Linq;
+global using global::System.Reactive;
+global using global::System.Reactive.Linq;
+global using global::System.Reactive.Subjects;
+global using global::System.Reactive.Threading.Tasks;
+global using global::System.Threading.Tasks;

src/ReactiveUI.AndroidSupport/ReactiveAppCompatActivity.cs

@@ -3,9 +3,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for full license information.
 
-using System.ComponentModel;
-using System.Diagnostics.CodeAnalysis;
-
 using Android.App;
 using Android.Content;
 using Android.Runtime;
@@ -194,4 +191,4 @@ protected override void Dispose(bool disposing)
 
         base.Dispose(disposing);
     }
-}
+}

src/ReactiveUI.AndroidSupport/ReactiveDialogFragment.cs

@@ -3,9 +3,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for full license information.
 
-using System.ComponentModel;
-using System.Diagnostics.CodeAnalysis;
-
 namespace ReactiveUI.AndroidSupport;
 
 /// <summary>

src/ReactiveUI.AndroidSupport/ReactiveFragment.cs

@@ -3,9 +3,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for full license information.
 
-using System.ComponentModel;
-using System.Diagnostics.CodeAnalysis;
-
 namespace ReactiveUI.AndroidSupport;
 
 /// <summary>

src/ReactiveUI.AndroidSupport/ReactiveFragmentActivity.cs

@@ -3,9 +3,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for full license information.
 
-using System.ComponentModel;
-using System.Diagnostics.CodeAnalysis;
-
 using Android.App;
 using Android.Content;
 using Android.Support.V4.App;

src/ReactiveUI.AndroidSupport/ReactivePagerAdapter.cs

@@ -4,7 +4,6 @@
 // See the LICENSE file in the project root for full license information.
 
 using System.Collections.Specialized;
-using System.Diagnostics.CodeAnalysis;
 
 using Android.Support.V4.View;
 using Android.Views;

src/ReactiveUI.AndroidSupport/ReactivePreferenceFragment.cs

@@ -3,9 +3,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for full license information.
 
-using System.ComponentModel;
-using System.Diagnostics.CodeAnalysis;
-
 using Android.Runtime;
 using Android.Support.V7.Preferences;
 

src/ReactiveUI.AndroidSupport/ReactiveRecyclerViewAdapter.cs

@@ -4,7 +4,6 @@
 // See the LICENSE file in the project root for full license information.
 
 using System.Collections.Specialized;
-using System.Diagnostics.CodeAnalysis;
 
 using Android.Support.V7.Widget;
 using Android.Views;

src/ReactiveUI.AndroidSupport/ReactiveRecyclerViewViewHolder.cs

@@ -3,8 +3,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for full license information.
 
-using System.ComponentModel;
-using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using System.Runtime.Serialization;