Add option to set and check list source settings by name

This makes it easier to select the intended settings value as the
underlying value often has no direct connection to the user facing name.

It also makes it possible to select list entries whos underlying value
changes frequently, but the user facing value does not.
(E.g. device IDs based on the input port compared to the device name)

tests/mocks/ui-helpers.cpp

@@ -20,6 +20,11 @@ int FindIdxInRagne(QComboBox *list, int start, int stop,
 	return -1;
 }
 
+void SetRowMatchingValueVisible(QComboBox *list, const QString &value,
+				bool show)
+{
+}
+
 bool DisplayMessage(const QString &msg, bool question, bool modal)
 {
 	return false;