Mens Underwear Market Size & Forecasts 2026-2035, By Segments (Price Range, Usage Occasion, Target Audience, Product Type, Fabric Material), Growth Opportunities, Innovation Landscape, Regulatory Shifts, Strategic Regional Insights (U.S., Japan, China, South Korea, UK, Germany, France), and Competitive Dynamics (Hanesbrands, Fruit of the Loom, Calvin Klein, Jockey, Tommy Hilfiger)