terminaldata: add No, Nc, Common types for SW contacts

Extend TerminalData::Type enum with three new semantic values:
- No     : Normally Open terminal of a switch (SW) contact
- Nc     : Normally Closed terminal of a switch (SW) contact
- Common : Common terminal of a switch (SW) contact

Update typeToString() and typeFromString() accordingly.
Fully backward compatible: existing Generic/Inner/Outer types
are unchanged. Elements without typed terminals fall back
to the previous behavior (first 2 named terminals).

terminal: expose terminalType() as public accessor

Add Terminal::terminalType() returning the TerminalData::Type
of this terminal. This allows crossrefitem and other consumers
to filter terminals by semantic role (No, Nc, Common) without
accessing TerminalData internals directly.

terminaleditor: add No, Nc, Common entries to type combobox

Expose the three new TerminalData types (No, Nc, Common) in
the element editor UI so users can assign a semantic role to
each terminal of a SW contact element.

Also fix a pre-existing bug in updateForm() where m_type_cb
was incorrectly using m_orientation_cb->findData() instead
of m_type_cb->findData(), preventing the type from being
restored correctly when selecting a terminal.

terminaleditor: add No, Nc, Common entries to type combobox

Expose the three new TerminalData types (No, Nc, Common) in
the element editor UI so users can assign a semantic role to
each terminal of a SW contact element.

Also fix a pre-existing bug in updateForm() where m_type_cb
was incorrectly using m_orientation_cb->findData() instead
of m_type_cb->findData(), preventing the type from being
restored correctly when selecting a terminal.

sources/properties/terminaldata.cpp

@@ -174,6 +174,12 @@ QString TerminalData::typeToString(TerminalData::Type type)
 			return QString("Inner");
 		case Outer :
 			return QString("Outer");
+		case No :
+			return QString("No");
+		case Nc :
+			return QString("Nc");
+		case Common :
+			return QString("Common");
 	}
 	return QString("Generic");
 }
@@ -193,6 +199,12 @@ TerminalData::Type TerminalData::typeFromString(const QString &string)
 		return TerminalData::Inner;
 	} else if (string == "Outer") {
 		return TerminalData::Outer;
+	} else if (string == "No") {
+		return TerminalData::No;
+	} else if (string == "Nc") {
+		return TerminalData::Nc;
+	} else if (string == "Common") {
+		return TerminalData::Common;
 	} else {
 		qDebug() << "TerminalData::typeFromString, argument string is invalid"
 					" failsafe type 'TerminalData::Generic' is returned";