CSSTUDIO-3597 Create a new instance of macros in EmbeddedDisplayWidget.getEffectiveMacros().

[abrahamwolk]

In a7e5d4c (part of #3475), the @Override method EmbeddedDisplayWidget.getEffectiveMacros() was removed in order to remove the LCID macro.

A side-effect of this was that no new instance of Macros was created when calling the function EmbeddedDisplayWidget.getEffectiveMacros(). This in turn leads to the firePropertyChange()-functionality stopping to work properly, since it contains the optimization that listeners should not be updated if the new value is equal() to the old value:

phoebus/app/display/model/src/main/java/org/csstudio/display/builder/model/properties/PropertyChangeHandler.java

Lines 167 to 169 in ed9fce4

	// Any change at all?
	if (new_value != null && old_value != null && !forceNotify && new_value.equals(old_value))
	return;

A concrete example to illustrate the problem is the following: consider an OPI A.bob that contains (1) an embedded display Widget of the name "EmbeddedDisplay" and (2) a script of the following form:

embeddedDisplayWidget = ScriptUtil.findWidgetByName(widget, "EmbeddedDisplay")
macros = embeddedDisplayWidget.getEffectiveMacros()
macros.add("NewMacro", "This is a new macro binding")
embeddedDisplayWidget.propMacros().setValue(macros)

This pull request reinstates the creation of a new instance of Macros when calling EmbeddedDisplayWidget.getEffectiveMacros(), which leads to firePropertyChange() notifying the embedded display of the change.

I am not sure if this is the best way to fix the issue, or not. It does seem to me, however, that calling embeddedDisplayWidget.propMacros().setValue(macros) with a valid argument should correctly update the embedded display.

I have tested the change manually.