Fix to handle Cancellation Token Tasks for ReactiveCommand.CreateFrom…

…Task (#3704)

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[Contribute](https://github.com/reactiveui/reactiveui#contribute)
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**What kind of change does this PR introduce?**
<!-- Bug fix, feature, docs update, ... -->

Fix for #1245
Fix for #2153
Fix for #3450

**What is the current behavior?**
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ReactiveCommand does not properly support Cancellation tokens properly
for CreateFromTask due to an underlying issue in System.Reactive

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

Fix the issues with the base functions within ReactiveCommand due to an
issue with Observable.FromAsync from System.Reactive by using a new
ObservableMixins.FromAsyncWithAllNotifications as the new function, this
extends Observable.FromAsync handling the error bubbling as required.

ObservableMixins.FromAsyncWithAllNotifications can be used to transform
a Cancellation Task into an Observable producing the expected
cancellation, errors and results.

**What might this PR break?**

ReactiveCommand.CreateFromTask will now handle exceptions as expected,
any existing workarounds could be removed once tested with actual
implementation in end users code.

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

**Other information**:

Co-authored-by: @idg10 - created the base code in #3556

src/ReactiveUI.Fody.Analyzer.Test/ReactiveUI.Fody.Analyzer.Tests.csproj

@@ -2,6 +2,7 @@
   <PropertyGroup>
     <TargetFrameworks>net472;net6.0</TargetFrameworks>
     <IsPackable>false</IsPackable>
+    <NoWarn>$(NoWarn);MSB3243</NoWarn>
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4" />

src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.DotNet6_0.verified.txt

@@ -695,6 +695,9 @@ namespace ReactiveUI
     }
     public class ReactiveCommand<TParam, TResult> : ReactiveUI.ReactiveCommandBase<TParam, TResult>
     {
+        protected ReactiveCommand([System.Runtime.CompilerServices.TupleElementNames(new string?[]?[] {
+                "Result",
+                "Cancel"})] System.Func<TParam, System.IObservable<System.ValueTuple<System.IObservable<TResult>, System.Action>>> execute, System.IObservable<bool>? canExecute, System.Reactive.Concurrency.IScheduler? outputScheduler) { }
         protected ReactiveCommand(System.Func<TParam, System.IObservable<TResult>> execute, System.IObservable<bool>? canExecute, System.Reactive.Concurrency.IScheduler? outputScheduler) { }
         public override System.IObservable<bool> CanExecute { get; }
         public override System.IObservable<bool> IsExecuting { get; }

src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.DotNet7_0.verified.txt

@@ -695,6 +695,9 @@ namespace ReactiveUI
     }
     public class ReactiveCommand<TParam, TResult> : ReactiveUI.ReactiveCommandBase<TParam, TResult>
     {
+        protected ReactiveCommand([System.Runtime.CompilerServices.TupleElementNames(new string?[]?[] {
+                "Result",
+                "Cancel"})] System.Func<TParam, System.IObservable<System.ValueTuple<System.IObservable<TResult>, System.Action>>> execute, System.IObservable<bool>? canExecute, System.Reactive.Concurrency.IScheduler? outputScheduler) { }
         protected ReactiveCommand(System.Func<TParam, System.IObservable<TResult>> execute, System.IObservable<bool>? canExecute, System.Reactive.Concurrency.IScheduler? outputScheduler) { }
         public override System.IObservable<bool> CanExecute { get; }
         public override System.IObservable<bool> IsExecuting { get; }

src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.DotNet8_0.verified.txt

@@ -695,6 +695,9 @@ namespace ReactiveUI
     }
     public class ReactiveCommand<TParam, TResult> : ReactiveUI.ReactiveCommandBase<TParam, TResult>
     {
+        protected ReactiveCommand([System.Runtime.CompilerServices.TupleElementNames(new string?[]?[] {
+                "Result",
+                "Cancel"})] System.Func<TParam, System.IObservable<System.ValueTuple<System.IObservable<TResult>, System.Action>>> execute, System.IObservable<bool>? canExecute, System.Reactive.Concurrency.IScheduler? outputScheduler) { }
         protected ReactiveCommand(System.Func<TParam, System.IObservable<TResult>> execute, System.IObservable<bool>? canExecute, System.Reactive.Concurrency.IScheduler? outputScheduler) { }
         public override System.IObservable<bool> CanExecute { get; }
         public override System.IObservable<bool> IsExecuting { get; }

src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.Net4_7.verified.txt

@@ -693,6 +693,9 @@ namespace ReactiveUI
     }
     public class ReactiveCommand<TParam, TResult> : ReactiveUI.ReactiveCommandBase<TParam, TResult>
     {
+        protected ReactiveCommand([System.Runtime.CompilerServices.TupleElementNames(new string?[]?[] {
+                "Result",
+                "Cancel"})] System.Func<TParam, System.IObservable<System.ValueTuple<System.IObservable<TResult>, System.Action>>> execute, System.IObservable<bool>? canExecute, System.Reactive.Concurrency.IScheduler? outputScheduler) { }
         protected ReactiveCommand(System.Func<TParam, System.IObservable<TResult>> execute, System.IObservable<bool>? canExecute, System.Reactive.Concurrency.IScheduler? outputScheduler) { }
         public override System.IObservable<bool> CanExecute { get; }
         public override System.IObservable<bool> IsExecuting { get; }