Bronquite crônicaA 52-week, Placebo- and Active- Controlled (Roflumilast, Daliresp® 500µg) Study to Evaluate the Efficacy and Safety of Two Doses of CHF6001 DPI (Tanimilast) as add-on to Maintenance Triple Therapy in Subjects With COPD and Chronic Bronchitis. (PILLAR) - PILLAR - Chiesi Farmaceutici S.p.A.