[BUG] Go to Definition on a source-generated method doesn't work

[arunchndr]

From vscode-dotnettools created by svick: microsoft/vscode-dotnettools#457

Describe the Issue

It seems that using Go to Definition on a partial method whose definition comes from a source generator does not work.

Steps To Reproduce

1. Create a new .Net 7 project.

2. Add the following code:

   using System;
   using System.Text.RegularExpressions;
   
   partial class Target
   {
       [GeneratedRegex("abc|def", RegexOptions.IgnoreCase, "en-US")]
       private static partial Regex AbcOrDefGeneratedRegex();
   
       static void Main()
       {
           Console.WriteLine(AbcOrDefGeneratedRegex().Match("foo"));
       }
   }

3. Use Go to Definition on AbcOrDefGeneratedRegex().

4. Error "Request textDocument/definition failed." pops up. The log contains:

[Error - 4:09:41 PM] [LanguageServerHost]System.UriFormatException: Invalid URI: The format of the URI could not be determined.
   at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind, UriCreationOptions& creationOptions)
   at Microsoft.CodeAnalysis.LanguageServer.ProtocolConversions.CreateAbsoluteUri(String absolutePath) in /_/src/Features/LanguageServer/Protocol/Extensions/ProtocolConversions.cs:line 174
   at Microsoft.CodeAnalysis.LanguageServer.ProtocolConversions.<TextSpanToLocationAsync>g__ConvertTextSpanToLocation|30_0(Document document, TextSpan span, Boolean isStale, CancellationToken cancellationToken) in /_/src/Features/LanguageServer/Protocol/Extensions/ProtocolConversions.cs:line 464
   at Microsoft.CodeAnalysis.LanguageServer.ProtocolConversions.TextSpanToLocationAsync(Document document, TextSpan textSpan, Boolean isStale, Nullable`1 context, CancellationToken cancellationToken) in /_/src/Features/LanguageServer/Protocol/Extensions/ProtocolConversions.cs:line 429
   at Microsoft.CodeAnalysis.LanguageServer.Handler.AbstractGoToDefinitionHandler.GetDefinitionAsync(TextDocumentPositionParams request, Boolean typeOnly, RequestContext context, CancellationToken cancellationToken) in /_/src/Features/LanguageServer/Protocol/Handler/Definitions/AbstractGoToDefinitionHandler.cs:line 61
   at Microsoft.CommonLanguageServerProtocol.Framework.QueueItem`3.StartRequestAsync(TRequestContext context, CancellationToken cancellationToken) in /_/src/Features/LanguageServer/Microsoft.CommonLanguageServerProtocol.Framework/QueueItem.cs:line 176
[Error - 4:09:41 PM] Request textDocument/definition failed.
  Message: Invalid URI: The format of the URI could not be determined.
  Code: -32000 
[object Object]

Environment Information

• Latest release (v0.3.21) or pre-release version Dev Kit extension (v0.4.8)
• v2.0.416 of C# extension

[arunchndr]

Consistent repro, but only with C# Dev Kit installed. cc: @dibarbet in case this came up in the uri support context.

[jasonmalinowski]

Duplicate of #6426.