gh-104855: Update Tkinter tests for Tcl/Tk 8.7 and 9.0 (GH-120824)

The tests are now passed with the current version of Tcl/Tk under
development (8.7b1+ and 9.0b3+).

The following changes were also made to make the tests more flexible:

* Helper methods like checkParam() now interpret the expected error message
  as a regular expression instead of a literal.
* Add support of new arguments in checkEnumParam():
  - allow_empty=True skips testing with empty string;
  - fullname= specifies the name for error message if it differs from the
    option name;
  - sort=True sorts values for error message.
* Add support of the allow_empty argument in checkReliefParam():
  allow_empty=True adds an empty string to the list of accepted values.
* Attributes _clip_highlightthickness, _clip_pad and  _clip_borderwidth
  specify how negative values of options -highlightthickness, -padx, -pady
  and -borderwidth are handled.
* Use global variables for some common error messages.

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

Lib/test/test_tcl.py

@@ -219,10 +219,18 @@ class TclTest(unittest.TestCase):
         with open(filename, 'wb') as f:
             f.write(b"""
             set a "<\xed\xa0\xbd\xed\xb2\xbb>"
+            """)
+        if tcl_version >= (9, 0):
+            self.assertRaises(TclError, tcl.evalfile, filename)
+        else:
+            tcl.evalfile(filename)
+            self.assertEqual(tcl.eval('set a'), '<\U0001f4bb>')
+
+        with open(filename, 'wb') as f:
+            f.write(b"""
             set b "<\\ud83d\\udcbb>"
             """)
         tcl.evalfile(filename)
-        self.assertEqual(tcl.eval('set a'), '<\U0001f4bb>')
         self.assertEqual(tcl.eval('set b'), '<\U0001f4bb>')
 
     def testEvalFileException(self):