interpreter: canonicalize when initializing search paths dynamically (#8299)

Dual-Root Mismatch in RustPython:
Unlike CPython, RustPython manages the standard library
in two separate locations in the workspace:
 - Workspace 'Lib/': Contains the test suite ('Lib/test/...') and
   standard library files.
 - crates/pylib/Lib/: A helper directory used for packaging.
   'crates/pylib/Lib' is a symlink pointing to the real workspace '../../Lib/'.

Runtime Directory Discrepancy:
 - 'sys.path' contains 'crates/pylib/Lib' (the path to the symlink).
 - Thus, when 'test.support' is imported, its '__file__' is resolved relative
   to the symlink: '/opt/RustPython/crates/pylib/Lib/test/support/__init__.py'.
 - Consequently, 'STDLIB_DIR' resolves to the symlink root:
   '/opt/RustPython/crates/pylib/Lib'.
 - However, since 'test_program.py' is executed directly from the workspace,
   its 'pkg_dir' is: '/opt/RustPython/Lib/test/test_unittest/testmock'.
 - When 'os.path.relpath(pkg_dir, top_dir)' is called:
   ---
   os.path.relpath(
       "/opt/RustPython/Lib/test/test_unittest/testmock",
       "/opt/RustPython/crates/pylib/Lib"
   )
   # Result: "../../../Lib/test/test_unittest/testmock"
   ---
   Because the relative path starts with '..', the assertion fails.

Assisted-by: Gemini

Lib/test/test_unittest/test_program.py

@@ -505,7 +505,6 @@ class TestCommandLineArgs(unittest.TestCase):
 
         self.assertEqual(program.testNamePatterns, ['*foo*', '*bar*', '*pat*'])
 
-    @unittest.expectedFailureIf(sys.platform != "win32", "TODO: RUSTPYTHON")
     def testSelectedTestNamesFunctionalTest(self):
         def run_unittest(args):
             # Use -E to ignore PYTHONSAFEPATH env var

src/interpreter.rs

@@ -57,7 +57,23 @@ fn setup_dynamic_stdlib(vm: &mut crate::VirtualMachine) {
     use rustpython_vm::common::rc::PyRc;
 
     let state = PyRc::get_mut(&mut vm.state).unwrap();
-    let paths = collect_stdlib_paths();
+    let paths: Vec<String> = collect_stdlib_paths()
+        .into_iter()
+        .map(|p| {
+            std::fs::canonicalize(&p)
+                .map(|canonical| {
+                    let s = canonical.to_string_lossy();
+                    #[cfg(windows)]
+                    {
+                        if let Some(stripped) = s.strip_prefix(r"\\?\") {
+                            return stripped.to_owned();
+                        }
+                    }
+                    s.into_owned()
+                })
+                .unwrap_or(p)
+        })
+        .collect();
 
     // Set stdlib_dir to the first stdlib path if available
     if let Some(first_path) = paths.first() {