model: promote `full_name` to MEntity

Signed-off-by: Jean Privat <jean@pryen.org>
model: add `full_name` to entities that miss one

Signed-off-by: Jean Privat <jean@pryen.org>
model: promote `c_name` from abstract-compiler to model

Signed-off-by: Jean Privat <jean@pryen.org>