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This section details on the original issue you should resolve

<issue_title>Offer to add usings for fully qualified names</issue_title>
<issue_description>It would be nice to have a codefix that offered to add usings for a fully qualified type and then simplified the name.

so if I had this:

publicstaticasyncSystem.Threading.Tasks.Task<string>GetGoodDealsAsync(){usingHttpClientclient=newHttpClient();usingHttpResponseMessageresponse=awaitclient.GetAsync("http://good-deals.com/");usingHttpContentcontent=response.Content;stringresult=awaitcontent.ReadAsStringAsync();return$"Here are the good deals:{result}";}

it would offer to do this:

usingSystem.Threading.Tasks;publicstaticasyncTask<string>GetGoodDealsAsync(){usingHttpClientclient=newHttpClient();usingHttpResponseMessageresponse=awaitclient.GetAsync("http://good-deals.com/");usingHttpContentcontent=response.Content;stringresult=awaitcontent.ReadAsStringAsync();return$"Here are the good deals:{result}";}```</issue_description><agent_instructions>Copilot, you're going to be creating a wholenewfeature here.1. this will be arefactoring.   So you will be creating aCodeRefactoringProvider.2.This will workfor C# andVB.Butwe're just going to start by making C# work.3. You'll need to create an `AbstractAddImportCodeRefactoringProvider`in `Microsoft.CodeAnalysis.Features`.  This can sit next toAbstractAddImportCodeFixProvider.cs4. The refactoring willworkinthefollowingfashion.Therefactoring will startwith the location the useris at,and will seeif itis on some name that binds to anamespace,and has a type name accessed off of it.  Note thatthis may beas simpleas `System.Console` oras complexas `global::System.Console` or `System.Collections.Generic.List<int>` etc.  Becausethisisin the shared 'Features' layer,you should use `ISyntaxFactsService` todo the analysis here so that it will workfor VB/C#.5. If you find such anamespacename,then you will offer the user a code action to `Add import and simplify type name`.6. Whenthis code action runs,it willdo3 things:1. It willadd the `using` to the proper scope(namespace or compilation unit).You canuse `IAddImportsService` to helpwiththis.2. It will then bothadd the `Simplifier.Annotation` annotation to thenamespace(or possiblynamespace+type)name thatit wasinvoked offof.This waythe codeaction infrastructurewill attemptto removethat superfluousname afterthe `using`is added.3. It will go through the file lookingfor types or expressions that startwith some name,and will checkif that nameis a type-namein thenewnamespace it's about toadd a `using`for.  These type names may now binddifferently,or become ambiguous.  So the refactoring should attempt to bind the current name,and replace itwith `SyntaxGenerator.TypeExpression(typeSymbol,true/false)`so thatthenameisnow qualifiedappropriately.  If thenameisambiguous,this willstay.Butif itis notambiguous, the code action infrastructurewill remove that qualification that youadded.1. You will then need to makea C#specificsubclass of yourabstractcoderefactoringprovider.Thereshould be almost nothinginthis.  It will exist just to properlyexport the `[ExportCodeRefactoringProvider(...)]`with apropername and language binding.Finally,add a lot of testsforthis.Add anew `AddUsingCodeRefactoringTests.cs` that sits next to `AddUsingTests.cs`.  This should use the VerifyCS patternlike `usingVerifyCS=CSharpCodeRefactoringVerifier<...>;`pattern.Test all your logic extensively.  Importantly, test simplificationin all the interesting places a qualified type name could show upin a type-onlylocation(like an inheritance list, parameter type,return type,typeof, `new T`, etc.).   And all the placeswhere it could start an expression, and validate those.Then, we want to test extensively that the logic to qualify existing names, and have them either become unqualified(ifthereis no ambiguity) orstay qualified(ifthereis) works.</agent_instructions>##Comments onthe Issue(youare @copilotinthissection)<comments></comments>