Fix test location URI construction on Linux/Mac (#2129)

Use vscode.Uri.file instead of vscode.Uri.parse with hard-coded
'file:///' prefix. On Linux/Mac, file paths start with '/' so
combining 'file:///' + '/home/user/...' produces 'file:////home/...'
(four slashes) which is an invalid URI.

vscode.Uri.file correctly handles platform differences, matching
the existing pattern used throughout SolutionExplorer.fs.

Closes #2117

Co-authored-by: Repo Assist (Copilot) <223556219+Copilot@users.noreply.github.com>

Author: github-actions[bot]

src/Components/TestExplorer.fs

@@ -933,7 +933,7 @@ module TestItem =
                     if String.IsNullOrEmpty path then
                         None
                     else
-                        vscode.Uri.parse ($"file:///{path}", true) |> Some
+                        vscode.Uri.file path |> Some
                 with e ->
                     logger.Debug($"Failed to parse test location uri {path}", e)
                     None