Function set_cell_hyperlink 

pub fn set_cell_hyperlink(
    ws: &mut WorksheetXml,
    rels: &mut Relationships,
    cell: &str,
    link: &HyperlinkType,
    display: Option<&str>,
    tooltip: Option<&str>,
) -> Result<()>

Set a hyperlink on a cell.

For external URLs and email links, a relationship entry is created in the worksheet .rels file with TargetMode="External". For internal sheet references, only the location attribute is set on the hyperlink element (no relationship is needed).

If a hyperlink already exists on the cell, it is replaced.