Does Article 49 TFEU in conjunction with Article 54 TFEU preclude a national rule under which compulsory contributions to an occupational pension scheme made by a non-resident taxpayer (on the basis of his membership of a bar association in the Member State, which is mandatory on professional grounds for the purposes of his activity carried on in several Member States) are not treated as deductible from income within the framework of limited tax liability, whereas in the case of resident taxpayers national law permits their deduction from income up to a specific ceiling within the framework of unlimited tax liability?