review feat(model): annotes getter and setter with a CtRole

[tdurieux]

This PR is related to #1368

TODO tests

[monperrus]

per our discussion

• type is for expression type (no comment, no type access)
• no role in reference interfaces
• remove contract all getters annotated
• split MEMBER in CONSTRUCTOR/FIELD/EXECUTABLE/NESTED_TYPE

[monperrus]

@surli OK for merge for me, please check.

This will probably be adjusted later, but this is a really good start, thanks @tdurieux

[surli]

Why not keeping PACKAGE here, it seems clearer?

[monperrus]

because it is more explicit, the role is to be a subpackage of another one

[surli]

because it is more explicit, the role is to be a subpackage of another one

Ok I saw the usage after asking.