fix(@angular/build): normalize roots to POSIX in test discovery for Windows compatibility

Ensures that project and workspace root paths are converted to POSIX format before being used to determine relative test file paths. This fixes an issue on Windows where mixed path separators (backslashes in roots, forward slashes in file paths) caused test discovery to fail to correctly generate entry point names.

Author: clydin

packages/angular/build/src/builders/unit-test/test-discovery.ts

@@ -129,7 +129,7 @@ export function generateNameFromPath(
   roots: string[],
   removeTestExtension: boolean,
 ): string {
-  const relativePath = removeRoots(testFile, roots);
+  const relativePath = removeRoots(testFile, roots.map(toPosixPath));
 
   let startIndex = 0;
   // Skip leading dots and slashes