BuiltinsWriterVisitor: Replace dynamic subtype abstract methods with overridable default implementations, throwing NotImplementedException

[zspitz]

There are currently three classes that inherit from BuiltinsWriterVisitor:

• CodeWriterVisitor
• FactoryMethodsWriterVisitor
• ToStringMethodsWriterVisitor

We're planning on adding two more:

• DebugViewWriterVisitor
• DynamicLinqWriterVisitor

Of all of these, only CodeWriterVisitor provides implementations for the dynamic submethods: WriteBinaryOperationBinder, WriteConvertBinder etc. All the others handle everything in VisitDynamic.

We could move these from abstract to virtual methods in BuiltinsWriterVisitor, throwing a NotImplementedException in the default implementation.

Alternatively, we could move these abstract methods out to CodeWriterVisitor, where they could be changed to non-overridable.

[zspitz]

70 is a better choice than throwing handled exceptions.