Function render_horizontal_scrollbar 

pub fn render_horizontal_scrollbar(
    frame: &mut Frame<'_>,
    hs_area: Rect,
    title_width: u16,
    fragmap_col_width: u16,
    total_clusters: usize,
    fragmap_available_width: usize,
    h_scroll_offset: usize,
)

Render the horizontal scrollbar for the fragmap columns.