Decapitalize drive letter in rootFolder during test collection

Fixes microsoft#8627. When the path of an actual test file (given by
vscode.Uri.fsPath) is later compared against the fullPath of a single
item of tests.TestFiles the drive letter mismatches and aborts further
actions despite the rest of the path is the same.

src/client/testing/common/services/discoveredTestParser.ts

@@ -39,6 +39,11 @@ export class TestDiscoveredTestParser implements discovery.ITestDiscoveredTestPa
         }
 
         for (const data of discoveredTests) {
+            // Fixes #8627 - Codelens does not open dropdown for parametrized tests.
+            if (process.platform === 'win32') {
+                const [driveLetter, ...rest] = data.root.split(path.sep);
+                data.root = [driveLetter.toLowerCase()].concat(...rest).join(path.sep);
+            }
             const rootFolder = {
                 name: data.root,
                 folders: [],