Moved some semantic test cases into syntax folder

mjtest/test/syntax_tests.py

 import shutil
-from mjtest.environment import Environment, TestMode
+from mjtest.environment import Environment, TestMode, TEST_MODES
 from mjtest.test.tests import TestCase, BasicTestResult
 from os import path
 
@@ -11,8 +11,10 @@ class BasicSyntaxTest(TestCase):
 
     def __init__(self, env: Environment, type: str, file: str):
         super().__init__(env, type, file)
-        self._should_succeed = not file.endswith(".invalid.mj")
-
+        if type != self.MODE and TEST_MODES.index(type) > TEST_MODES.index(self.MODE):
+            self._should_succeed = True
+        else:
+            self._should_succeed = not file.endswith(".invalid.mj")
     def should_succeed(self) -> bool:
         return self._should_succeed