Remove local DisposeWith use System.Reactive.Disposables.Fluent

[ChrisPulman]

What kind of change does this PR introduce?

update

What is the current behavior?

System.Reactive.Disposables.DisposeWith is a feature within ReactiveUI

What is the new behavior?

This pull request primarily updates the way disposable extension methods are referenced and used throughout the codebase. It removes the local implementation of DisposeWith and instead relies on the upstream System.Reactive.Disposables.Fluent package, which is now imported via global usings. Additionally, it updates some package versions and cleans up unnecessary using directives in test files.

Dependency and API usage updates:

• Removed the local DisposableMixins implementation (DisposeWith extension method) from DisposableMixins.cs since this functionality is now provided by System.Reactive.Disposables.Fluent.
• Added System.Reactive.Disposables.Fluent to global usings in GlobalUsings.cs for ReactiveUI, ReactiveUI.Maui, and ReactiveUI.AOTTests, enabling the use of DisposeWith throughout the codebase without explicit imports. [1] [2] [3]

Code cleanup:

• Removed redundant or unnecessary using directives from multiple test files in ReactiveUI.AOTTests to streamline the code and rely on global usings. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10]

What might this PR break?

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:

[Copilot]

Pull Request Overview

This PR refactors the disposable extension method usage throughout the ReactiveUI codebase by removing the local DisposeWith implementation and migrating to the upstream System.Reactive.Disposables.Fluent package. This change standardizes disposable handling and eliminates code duplication.

• Removes local DisposableMixins class containing custom DisposeWith implementation
• Adds System.Reactive.Disposables.Fluent to global usings across multiple projects
• Cleans up redundant using directives in test files to rely on global usings

Reviewed Changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/ReactiveUI/Mixins/DisposableMixins.cs	Completely removes the local DisposeWith extension method implementation
src/ReactiveUI/GlobalUsings.cs	Adds global using for System.Reactive.Disposables.Fluent
src/ReactiveUI.Maui/GlobalUsings.cs	Adds global using for System.Reactive.Disposables.Fluent
src/ReactiveUI.Blazor/GlobalUsings.cs	Adds global using for System.Reactive.Disposables.Fluent
src/ReactiveUI.Builder.WpfApp/Views/*.cs	Adds explicit using for System.Reactive.Disposables.Fluent
src/ReactiveUI.AOTTests/GlobalUsings.cs	Adds global using and removes unused System.Threading
src/ReactiveUI.AOTTests/*.cs	Removes redundant using directives now covered by global usings

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 35.05%. Comparing base (7776b48) to head (3a8c3f5).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4164      +/-   ##
==========================================
- Coverage   35.08%   35.05%   -0.04%     
==========================================
  Files         140      139       -1     
  Lines        6016     6013       -3     
  Branches      885      885              
==========================================
- Hits         2111     2108       -3     
  Misses       3743     3743              
  Partials      162      162              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.