TST/MNT: in pyside6 designer is named 'pyside6-designer', also disable designer plugin test on pyside6

disable the test for now (until custom pydm-widgets work in
pyside6-designer), so in the meantime we can enable all other tests
to run on pyside6 in automation.

Author: nstelter-slac

pydm/main_window.py

@@ -111,11 +111,14 @@ def __init__(
             QLibraryInfo.location(QLibraryInfo.BinariesPath),
             QLibraryInfo.location(QLibraryInfo.LibraryExecutablesPath),
         )
+
+        # look into mac and windows naming later
+        executable_name = "designer" if ACTIVE_QT_WRAPPER == QtWrapperTypes.PYQT5 else "pyside6-designer"
         for bin_path in possible_designer_bin_paths:
             if platform.system() == "Darwin":
                 designer_path = os.path.join(bin_path, "Designer.app/Contents/MacOS/Designer")
             elif platform.system() == "Linux":
-                designer_path = os.path.join(bin_path, "designer")
+                designer_path = os.path.join(bin_path, executable_name)
             else:
                 designer_path = os.path.join(bin_path, "designer.exe")
             if os.path.isfile(designer_path):

pydm/tests/test_plugins_import.py

@@ -1,5 +1,9 @@
-from ..widgets.qtplugin_base import qtplugin_factory
+import pytest
+from ..utilities import ACTIVE_QT_WRAPPER, QtWrapperTypes
+if ACTIVE_QT_WRAPPER == QtWrapperTypes.PYSIDE6:
+    pytest.skip("pydm with pyside6 does not support custom pydm-widgets yet in pyside6-designer!", allow_module_level=True)
 
+from ..widgets.qtplugin_base import qtplugin_factory
 
 def test_import_byte_plugin():
     # Byte plugin