Bug: The mouse_click function in wx/_interaction_helpers.py do not set focus to current control

[pbrod]

The mouse_click function in for wx located in traitsui/testing/tester/_ui_tester_registry/wx/_interaction_helpers.py do not set focus to current control. This result in test failures when testing the RangeTextEditor for wx, because
when editing the text part of a range control box and clicking on the OK button will not update the value of the HasTraits class
since the focus will not change in the test-envirionment as exemplified in the following test:

class NumberWithRangeEditor(HasTraits):
    """Dialog containing a RangeEditor in 'spinner' mode for an Int."""

    number = Int()

    traits_view = View(
        Item(label="Range should be 3 to 8. Enter 1, then press OK"),
        Item("number", editor=RangeEditor(low=3, high=8, mode="text",
                                          enter_set=True,
                                          auto_set=False)),
        buttons=["OK", "Cancel"],
    )

class TestRangeEditorText(BaseTestMixin, unittest.TestCase):
    def setUp(self):
        BaseTestMixin.setUp(self)

    def tearDown(self):
        BaseTestMixin.tearDown(self)

    @requires_toolkit([ToolkitName.qt, ToolkitName.wx]) 
    def test_text_editing(self):
        num = NumberWithRangeEditor()
        assert num.number == 0
        tester = UITester()
        with tester.create_ui(num) as ui:
            text = tester.find_by_name(ui, "number")
            displayed = text.inspect(DisplayedText())
            assert displayed == '3'
            assert num.number == 3
            text.perform(command.KeyClick("Backspace"))
            text.perform(command.KeyClick("4"))
            displayed = text.inspect(DisplayedText())
            assert displayed == '4'
            assert num.number == 3

            cancel_button = tester.find_by_id(ui, "Cancel")
            cancel_button.perform(command.MouseClick())

        assert num.number == 4