Add MIMIC-SBDH and MIMIC-III dataset classes and BioClinicalBERTAlcoholUse model

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Add MIMIC-SBDH and MIMIC-III dataset classes and BioClinicalBERTAlcoholUse model

• Implement MIMICSBDHDataset for SBDH annotations
• Add MIMICIIIDataset for MIMIC-III integration
• Introduce BioClinicalBERTAlcoholUse model for alcohol use classification
• Register new datasets and model in package init files
• Add metadata preparation for SBDH dataset