Fix password

[nstelter-slac]

Issue was when using designer, entering a password in "Property" window on right-side of screen would not save the encrypted password to the .ui file as expected, and password feature would not work.

This is because editing the "password" property would in-turn update the "protectedPassword" property,
but designer would not consider the "protectedPassword" property as having been edited, and would then not save it out to the .ui file.

Fix is to update the "protectedPassword" widget property directly with "setProperty" when the "password" is set, to make sure designer knows to save the "protectedPassword" value.

Widget-update code grabbed from the "update_property_for_widget" function in "pydm/widgets/designer_settings.py":

def update_property_for_widget(widget: QtWidgets.QWidget, name: str, value):
    """Update a Property for the given widget in the designer."""
    formWindow = QtDesigner.QDesignerFormWindowInterface.findFormWindow(widget)
    logger.info("Updating %s.%s = %s", widget.objectName(), name, value)
    if formWindow:
        formWindow.cursor().setProperty(name, value)
    else:
        setattr(widget, name, value)

[nstelter-slac]

To verify fix:

-open shell_command/shell_command.ui in designer
-select one of the buttons, check "passwordProtected" and enter "password"
-save in designer, and then run shell_command.ui again
-click on modified button, enter password, confirm the password is accepted

[YektaY]

Looks great. thank you