source-gen: Make doc string verbatim if necessary

If the documentation string contains quotes, make it a verbatim string
(enclosed in triple quotes).
Add NameWithTypeArguments and ExpressionIsh

NameWithTypeArguments will be used by BaseExpression, StaticExpression,
and MemberExpression.

NameWithTypeArguments, ExpressionIsh / Expression, BaseExpression /
StaticExpression / MemberExpression will be analogous to
TypeNameWithArguments, TypeIsh / Type, BaseType / QualifiedType.
Fix token order in RedHatTransformer.transformBaseType
Add BaseExpression