Remote Ischaemic Preconditioning Attenuates Thrombin-Mediated Conformational Activation of Platelet Glycoprotein IIb/IIIa, the Generation of Procoagulant Platelets, and Platelet Mitochondrial Membrane Depolarisation in Patients Receiving Antiplatelet Therapy: A Randomised Blinded Placebo-Controlled Study